With the advancement of the era, the demand for ultraviolet photodetectors in environmental monitoring and communication security continues to grow, leading to increasingly stringent performance requirements. In this case, self-driven ultraviolet photodetectors emerge to meet the needs of energy conservation and device miniaturization. However, conventional self-driven ultraviolet photodetectors still face some challenges such as low efficiency in photo-generated carrier separation, poor photoresponse performance, and limited response speed. Ferroelectric thin films with a high remnant polarization can form a depolarization field that penetrates the entire bulk material, enabling an effective separation of internally generated photo-generated electrons and holes. This provides a promising solution to the aforementioned issues. Pb(Zr_xTi1-x)O₃(PZT) is a typical ABO₃-type perovskite ferroelectric material. This material is widely used in ferroelectric memories, micro-electromechanical systems, and photodetectors due to its excellent ferroelectric, piezoelectric, and photoelectric properties. Extensive studies show that the composition significantly affects the crystal phase structure and ferroelectric properties of PZT thin films. However, its impact on the photoelectric performance requires a further systematic investigation. This work was to analyze the photoelectric characteristics of PZT thin films with different Zr/Ti ratios, in order to elucidate the influence of compositional modulation on the photoelectric effect.

Pb(Zr_xTi₁-x)O₃ ferroelectric thin films with different Zr/Ti ratios were prepared by a sol-gel method. The selected precursors and solvents were high-purity lead acetate [Pb(CH₃COO)₂·3H₂O], zirconium n-propoxide (C₁₂H₂₈O₄Zr), and titanium isopropoxide (C₁₂H₂₈O₄Ti) as sources for lead, zirconium, and titanium, respectively, glacial acetic acid as a chelating agent, and n-propanol as a stabilizer. Semitransparent gold electrodes were deposited on the surface of the thin films by a model VZZ-300 high-vacuum thermal evaporation system (VANNO Co., China) to fabricate self-driven ultraviolet photodetectors with an Au/PZT/FTO vertical structure. The crystal structure of the films was characterized by a model D8 Advance X-ray diffractometer (XRD, Bruker Co., USA). The surface roughness of the films was determined by an atomic force microscope (AFM, Bruker Dimension Edge Co., USA). The optical properties of the films were analyzed by a model UV-3600 Plus ultraviolet-visible-near-infrared spectrophotometer (UV-Vis-NIR, Shimadzu, Japan). The ferroelectric properties were measured by a model Precision LC II ferroelectric test system (Radiant Co., USA). The current-time (I-t) curves were obtained by a model Keithley 2400 source meter, with a 150 W ultraviolet-enhanced xenon lamp as a light source.

The XRD patterns indicate that the three prepared PZT thin films with different Zr/Ti ratios all exhibit a typical perovskite structure, and no diffraction peaks from impurity phases appear aside from those originating from the FTO substrate. As the Zr content increases, the surface morphology of the films transitions from elongated needle-like structures to island-like structures, and finally to wavy undulations. The lowest root mean square (RMS) roughness of 2.62 nm is obtained at a Zr/Ti ratio of 0.52:0.48. The remnant polarization first increases from 27.9 μC/cm² (Zr/Ti=0.49/0.51) to a maximum of 33.2 μC/cm² (Zr/Ti=0.52/0.48), and then decreases to 31.1 μC/cm² (Zr/Ti=0.55/0.45) as the Zr content increases. A higher remnant polarization is beneficial to forming a stronger built-in electric field, thereby improving the separation efficiency of photogenerated carriers. The PZT films with different Zr/Ti ratios are all wide-bandgap semiconductors (>3.6 eV). As the Zr content increases, the bandgap widens from 3.60 eV to 3.68 eV, showing a blue-shift trend. When a negative poling voltage is applied, the depolarization field inside the PZT aligns with the built-in field induced by the interfacial Schottky barrier, synergistically enhancing the driving force for carrier separation and leading to a significant increase in photocurrent. For the sample with a Zr/Ti ratio of 0.52:0.48 at a poling voltage of -2 V, the responsivity and detectivity reach 3.2 mA/W and 0.33×10¹¹ Jones, respectively. Even under a weak illumination of as low as 0.17929 mW/cm², the device still generates a photocurrent of 1.02 nA, demonstrating the excellent detection sensitivity.

Pb(Zr_xTi₁-x)O₃ ferroelectric thin films with different zirconium-to-titanium ratios (i.e., Zr/Ti=0.49:0.51, 0.52:0.48, 0.55:0.45) were fabricated by a sol-gel method, and self-driven ultraviolet photodetectors with an Au/PZT/FTO structure were constructed. The structural characterization revealed that all PZT thin films exhibited a pure perovskite phase with a good crystalline quality. The AFM analysis indicated that the film surfaces were smooth, dense, and displayed a uniform grain distribution. The ferroelectric property measurements further confirmed that all films with different Zr/Ti ratios showed characteristic ferroelectric hysteresis loops and possessed a high remnant polarization, having a maximum value of 33.2 μC/cm² at Zr/Ti=0.52:0.48. The results of photoelectric tests demonstrated that the device based on this optimal composition exhibited stable and reproducible photocurrent responses. At a poling voltage of -2 V, its responsivity and detectivity were significantly enhanced. In summary, the rational adjustment of the Zr/Ti ratio could effectively optimize both the ferroelectric properties of PZT thin films and the photoelectric characteristics of the corresponding devices. This work could innovatively utilize the inherent bulk depolarization field of PZT ferroelectrics as a driving force to achieve an efficient separation of photogenerated electron-hole pairs. Moreover, it could provide a systematic optimization strategy from the perspectives of compositional design and polarization modulation, offering an effective material- and physics-based solution to overcome the key bottlenecks of low responsivity and detectivity in self-driven ultraviolet photodetectors.

In this review, we summary various strategies for surface reconstruction of quantum dots, discuss the selection and design principles of surface and ligands for quantum dots applied in electroluminescence, and finally represent recent research progress in the integration of lead halide and its quantum dots with active-matrix displays. To further promote the realization of efficient full-color active drive LEDs, a key interim goal in the next step is to break through the pixelization technology for lead halide quantum dots, thereby achieving the integration of red, green, and blue colors onto the active-matrix TFT backplane simultaneously. Many scientific and technical issues need to be solved in this process. For instance, how to ensure that the morphology and photoelectric performance of the lead halide quantum dot film are not damaged during pixelization. The need for high resolution means that thousands of pixel points should be arranged very closely, having high requirements for the precise positioning of pixelization technology. In addition, avoiding color crosstalk caused by ion exchange between pixel points is also a technical problem that must be solved due to the easy ion exchange of halogen ions.

In summary, with the increasing service temperature of aero-engines, the abradable/environmental barrier coatings (A/EBCs) that match SiC_f/SiC ceramic matrix composites (CMCs) become a key research direction. This review represents the research progress of A/EBCs in material design, microstructural regulation and performance evaluation, and points out that the current challenges mainly include thermal expansion mismatch between conventional coating materials and CMC substrate, poor high-temperature stability of lubricants, difficult balance between multi-scale pore structure and multi-performance, and lack of standardized evaluation systems and test standards suitable for multi-field coupling service environment. In the future, the research and development of A/EBCs should focus on the multi-objective synergistic design of material composition, multi-scale microstructure and performance evaluation system. It is necessary to strengthen the analysis of failure mechanism under multi-physical field coupling environment, develop new high-temperature stable matrix and lubricant materials, realize the precise regulation of multi-scale pore and interface structure, and establish a standardized preparation and performance evaluation system. Through the breakthrough of the above key technologies, the comprehensive performance and service durability of A/EBCs will be effectively improved, so as to promote the leapfrog development of high-temperature sealing technology and provide an important support for the performance improvement of next-generation aero-engines.

In summary, SOCs thin film preparation technologies can form a diversified system, but some common challenges remain. Although vapor-phase technologies have excellent performance, they generally face high equipment costs and great difficulty in scaling up. Liquid-phase technologies are prone to film cracks or pores due to drying and sintering stress. Future research should focus on three core directions, i.e., 1) promoting intermediate and low-temperature operation, further expanding the low-temperature application range of batteries through interface regulation and film formation process optimization; 2) pursuing high performance, developing three-dimensional structured films to expand reaction interfaces and improve mass transfer and catalytic efficiency; and 3) accelerating commercialization, optimizing low-cost preparation processes combined with intelligent manufacturing technologies, and breaking through the key technical bottlenecks of new film formation technologies. Thin film preparation technology will continue to be a core breakthrough to solve the high-temperature dependence and performance attenuation of SOCs, promoting their transition from laboratory research to commercial application.

With the continuous pursuit of higher efficiency and larger thrust-to-weight ratio in aero-gas-turbine engines, the turbine inlet temperature has already exceeded 1300 ℃, imposing increasingly stringent requirements on the thermal resistance and protective capability of hot-section structural materials. Environmental barrier coatings (EBCs) have become a crucial technology to ensure efficient and reliable service of ceramic matrix composite (CMC) turbine components under such extreme working conditions. However, the service environment of EBCs is exceptionally complex. Coatings are continuously exposed to corrosive gaseous species within combustion products, among which the ingression and reaction of molten calcium-magnesium-aluminum-silicate (CMAS) deposits represent one of the most detrimental degradation mechanisms.

To mitigate CMAS-induced deterioration, numerous strategies have been proposed, including compositional modification (doping, high-entropy ceramics), structural design optimization (multilayer or graded coatings), and surface engineering (laser or ion beam treatments). Although these approaches can improve corrosion resistance to some extent, most of them inevitably alter the coating chemistry or structural system, which tends to induce thermal expansion mismatch with the substrate and promotes premature failure during thermal cycling. Therefore, how to enhance CMAS-corrosion resistance while maintaining thermomechanical compatibility remains a critical challenge. Laser glazing (LG) is a surface-modification technique that locally melts and rapidly solidifies the coating surface to form a dense glaze layer. It improves surface compactness and seals microdefects without altering the coating composition, thereby presenting a promising method for improving CMAS-corrosion resistance. In this work, laser glazing is introduced to enhance the CMAS-resistance of EBCs, and the CMAS-corrosion behavior together with the underlying improvement mechanisms are systematically investigated.

SiC ceramic substrates were purchased from Fuzhou Pengkun Optoelectronics Co., Ltd. The samples were cylindrical (diameter 25.4 mm, thickness 3 mm) and mechanically grit-blasted prior to coating deposition. Yb₂Si₂O₇/Si (YbDS) EBCs were deposited on the substrates by atmospheric plasma spraying (APS). Commercial Yb₂Si₂O₇ and Si powders (Shanghai Shuitian Materials Technology Co., Ltd.) were used, and the bond coat consisted of 90% (in mass fraction) Si and 10% Yb₂Si₂O₇. A picosecond ultraviolet pulsed-laser system was subsequently applied to modify the surface microstructure of APS YbDS coatings. Four sets of parameters (L1-L4) were obtained by adjusting the laser power (6 W or 20 W) and scanning speed (100-300 mm/s). CMAS bulk material was synthesized by high-temperature melting. CMAS powder was mixed with ethanol and uniformly brushed onto the coating surface, followed by drying to achieve a coating mass of 5 mg/cm². The coated samples were exposed at 1350 ℃ for 10, 60 h, and 120 h. After corrosion, the evolution of microstructure and phase composition was analyzed to reveal the degradation behavior.

The APS-prepared YbDS coating exhibited a surface roughness of ~3.7 μm and a porosity of ~4.87%, with typical APS defects such as pores, unmelted particles, and microcracks. After laser glazing, four modified surfaces were obtained. Among them, sample L2 demonstrated the most favorable structural morphology and was selected for subsequent corrosion tests. The L2 coating showed a reduced surface roughness of ~1.824 μm and a homogeneous, dense glaze layer of ~9.6 μm thickness. Moreover, the glazed surface phase completely transformed from Yb₂Si₂O₇ to Yb₂SiO₅. During CMAS corrosion, the YbDS coating surface was continuously covered by a loose mixture of Ca₂Yb₈(SiO₄)₆O₂ and CMAS residual glass. In contrast, the laser-modified L2 coating was covered by a compact Ca₂Yb₈(SiO₄)₆O₂ reaction layer. After corrosion, both coatings displayed Ca₂Yb₈(SiO₄)₆O₂ and secondary Yb₂Si₂O₇ phases; however, their structural evolution differed significantly. After 120 h of corrosion, the YbDS coating suffered severe structural degradation, including interfacial delamination and partial spallation in cross-sectional observations. Conversely, the L2 coating maintained structural integrity, and its corrosion depth was consistently lower under the same conditions.

The improved CMAS resistance of the L2 coating can be attributed to three synergistic mechanisms: Surface densification, Laser glazing produced a dense, continuous glaze layer that sealed APS-induced pores and cracks, effectively delaying CMAS infiltration pathways; Protective reaction-layer formation, The Yb₂SiO₅ glaze reacted with CMAS to form a dense Ca₂Yb₈(SiO₄)₆O₂ layer, which further hindered molten-salt penetration ;Enhanced non-wettability, Laser glazing significantly reduced surface roughness and improved hydrophobicity. As a result, molten CMAS appeared as aggregated hemispherical droplets rather than fully spreading, making it more easily removed by high-velocity gas flow during service.

The findings of this study demonstrate that laser glazing effectively enhances the CMAS-corrosion resistance of YbDS coatings. The improvement originates from the combined effects of surface densification, pore/crack sealing, phase transformation to Yb₂SiO₅, and subsequent formation of a compact Ca₂Yb₈(SiO₄)₆O₂ reaction layer during corrosion. Additionally, the smoother and less wettable glazed surface reduces the adhesion and spreading tendency of CMAS, enabling molten deposits to be removed more easily under aerodynamic forces. As a result, the degradation rate of the coating is substantially suppressed, delaying the propagation of corrosion-induced cracks and maintaining structural integrity over prolonged exposure. Moreover, the laser-induced modifications do not alter the coating architecture or introduce thermal expansion mismatch, making the technique compatible with existing EBC design frameworks. Overall, laser glazing represents a promising strategy for improving the durability and service lifetime of EBC systems in next-generation high-temperature aero-engine applications.

Phosphorus (P) is an essential nutrient for aquatic ecosystems. However, excessive phosphorus discharge into surface water is one of the primary causes of eutrophication, thus triggering algal blooms, degrading water quality, and threatening aquatic life as well as human health. It is widely recognized that even low concentrations of phosphorus can significantly accelerate eutrophication processes, making efficient phosphorus removal a critical issue in water pollution control. Among the existing treatment technologies, adsorption has attracted increasing attention due to its operational simplicity, high efficiency for low-concentration phosphorus, and limited risk of secondary pollution.

Coal fly ash is one of the most abundant industrial solid wastes that are generated in large quantities in coal-fired power plants. Although its comprehensive utilization rate is increased, a considerable fraction of fly ash is still disposed of by landfilling or stockpiling, posing long-term environmental risks. Fly ash is a promising precursor for the preparation of ceramic materials due to its high contents of SiO₂ and Al₂O₃. Moreover, the presence of Ca, Mg, and other alkaline components endows fly-ash-derived materials with a potential chemical affinity toward phosphate species. Transforming fly ash into functional ceramsite for water treatment therefore represents a typical "waste-to-resource" strategy.

Previous studies explored fly-ash-based ceramsite or related materials for phosphorus removal. However, most of them focused primarily on adsorption performance evaluation, while systematic optimization of preparation parameters and in-depth clarification of phosphorus removal mechanisms remained insufficient. Such limitations hinder the rational design and engineering application of these materials. In this work, fly ash was used as a main raw material, supplemented with municipal sludge, furnace slag, and cement to prepare porous ceramsite for phosphorus removal. The adsorption behavior, comprehensive physicochemical characterization, preparation conditions, and removal mechanism were systematically investigated.

Fly-ash-based ceramsite was prepared by a disc granulation method. Fly ash was mixed with municipal sludge as a pore-forming component, furnace slag as a functional additive, and cement as a binder. After granulation with deionized water, green pellets with a controlled particle size were obtained and subjected to preheating and high-temperature sintering. To optimize the preparation process, a Taguchi L25 (5⁶) orthogonal experimental design was employed, considering six factors, i.e., fly ash-to-sludge ratio, preheating temperature, preheating time, sintering temperature, sintering time, and heating rate. Phosphate removal efficiency was selected as an evaluation index to determine the optimal preparation parameters.

Batch adsorption experiments were conducted using simulated phosphate solutions prepared from potassium dihydrogen phosphate. The effects of dosage, initial pH value, coexisting ions, and humic acid were systematically investigated to evaluate adsorption adaptability under different water chemistry conditions. Adsorption isotherms were analyzed using the Langmuir, the Freundlich, the Sips, and the Dubinin-Radushkevich models, while adsorption kinetics were interpreted using pseudo-first-order, pseudo-second-order models, i.e., Elovich, and intraparticle diffusion models.

The physicochemical properties and adsorption mechanisms of the ceramsite were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, the leaching risk of heavy metals was also assessed using standard toxicity characteristic leaching procedures to evaluate environmental safety.

The results of orthogonal experimental analysis reveal that sintering temperature is the most dominant factor affecting phosphate removal performance, following by sintering time and heating rate. The excessively high sintering temperature leads to pore collapse and crystallization of stable mineral phases, thereby reducing adsorption capacity. The optimal preparation conditions obtained are a fly ash-to-municipal sludge ratio of 7∶3, preheating at 600 ℃ for 5 min, sintering at 1050 ℃ for 5 min, and a heating rate of 5 ℃/min. Under the optimal conditions, the ceramsite achieves a phosphate removal efficiency of 90.77%, which is significantly higher than that of all orthogonal experimental groups.

The SEM images show that the optimized ceramsite has a rough surface with abundant interconnected pores, originating from the thermal decomposition of organic matter in municipal sludge and gas evolution during high-temperature reactions. The XRD patterns indicate that mullite and anorthite are the dominant crystalline phases, while Ca- and Mg-containing components are retained in reactive forms. The results of batch experiments demonstrate that phosphate removal efficiency increases with increasing dosage but decreases under strong alkaline conditions. The ceramsite maintains effective phosphorus removal in a wide range of pH values, with optimal performance under weakly acidic to neutral conditions.

The coexisting anions exhibit varying degrees of inhibition on phosphate removal, following a decreasing order CO₃^2- >HCO₃^- > SO₄^2- > NO₃^- > Cl^-, whereas common monovalent cations show a negligible influence. In contrast, the presence of Ca²⁺ and Mg²⁺ significantly enhances phosphate removal due to additional precipitation reactions. Humic acid notably suppresses adsorption via competing for active sites and altering phosphate speciation.

Adsorption isotherm analysis shows that the Langmuir and Sips models both fit the experimental data, while the Sips model provides a better physical interpretation, indicating a heterogeneous surface adsorption. The kinetic analysis reveals that the pseudo-first-order model can describe the adsorption process, indicating that surface reactions are dominant the rate-controlling step. The XPS spectra confirm the formation of Ca- and Mg-phosphate species on the ceramsite surface after adsorption, showing that phosphate removal occurs based on a synergistic mechanism involving physical adsorption and chemical precipitation.

The results of leaching tests indicate that the concentrations of heavy metals released from the ceramsite are well below regulatory limits, having its environmental safety for water treatment applications.

A fly-ash-based ceramsite was prepared using municipal sludge and furnace slag as auxiliary components for efficient phosphate removal in water. The ceramsite exhibited a high removal efficiency, a broad pH value adaptability, and a stable performance under complex water chemistry conditions via systematic optimization of preparation parameters and comprehensive adsorption studies. The phosphate removal mechanism was dominated due to the synergistic effect of surface adsorption and Ca/Mg-induced chemical precipitation. Moreover, the ceramsite showed a negligible heavy-metal leaching risk, indicating a good environmental compatibility. This study could provide a feasible approach for the large-scale resource utilization of fly ash and offer a promising adsorbent for phosphorus control in aquatic environments.

Although composite titanium salt coagulants demonstrate excellent performance, there are still some issues and challenges that need to be addressed. Future research can focus on the following aspects: (a) Enhancing Adaptability to Real Water Bodies. Currently, the complex composition of various actual water bodies imposes higher demands on the application of composite titanium salt coagulants. To ensure stable and efficient coagulation performance under complex water quality conditions, future efforts should focus on developing novel composite titanium salt coagulants with stronger specificity and broader applicability, thereby meeting the needs of more complex and demanding application scenarios. (b) Lower- Cost Preparation of Composite Titanium Salt Coagulants. At present, the preparation of composite titanium salt coagulants largely relies on complex processes such as SAT, ED, and sol-gel methods, which hinders their large-scale application. Future research should aim to develop simpler, greener, and more economically viable preparation pathways—for instance, utilizing industrial by-products or waste materials as raw materials—while optimizing the preparation process to reduce energy consumption and production costs. (c) Ensuring Ecological and Health Safety. Current research on the toxicity assessment of titanium-based coagulants has predominantly focused on TiCl₄ and Ti(SO₄)₂. Future studies should strengthen investigations into titanium residue and its ecotoxicological effects during the use of composite titanium salt coagulants. Meanwhile, it is essential to employ a wider range of aquatic organisms (e.g., fish, shellfish, and aquatic plants) for ecotoxicity studies, and to further explore the migration, transformation, and long-term accumulation of residual titanium in water bodies and organisms. This will provide a scientific basis for comprehensively safeguarding water environments and human health.

In transition towards a decarbonized energy system globally, hydrogen plays a crucial role as a zero carbon energy carrier. In this context, solid oxide electrolysis cell (SOEC) technology with its advantages in high-temperature operation significantly reduces material costs and improves overall system energy efficiency, compared to low-temperature solutions such as alkaline and proton exchange membrane electrolysis. SOEC system adopts a non-precious metal ceramic structure. When operating at 650-1000 ℃, electrochemical kinetics acceleration mechanism achieves a conversion efficiency of > 80%, providing a feasible approach to reduce cost of green hydrogen leveling. The existing domestic demonstration projects are limited to a scale of tens to hundreds of kilowatts, and the commercial implementation needs to break through bottleneck of "three highs and one low", thus increasing power density of fuel cell stack, extending its service life, and optimizing system integration, while reducing assets and operation and maintenance costs. Solving these obstacles requires collaborative efforts in three major fields, and innovation in materials and structures must break through conventional design framework of electrodes, electrolytes, and sealing glass. With precise microstructure design and interface stress control, system can maintain a high current density of 2 A·cm^-2, while controlling degradation rate at 1 mV per thousand hours, significantly extending lifespan of battery pack. Multi-energy coupling optimization is crucial, which requires integrating the SOEC with industrial waste heat and renewable resources, thus utilizing low-grade thermal energy (i.e., 200-300 ℃), efficiently offsetting internal heating demand, reducing external electricity consumption by approximately 30%, and comprehensively improving energy utilization efficiency. For those localized supply chains, establishing a complete domestic production capacity from precursor powder to single cell manufacturing, stacking and assembly to system integration is particularly crucial. The goal is to control stacking cost at RMB 2500 per kW and achieve an operating life of 5×10⁴ h, laying a foundation for large-scale applications. At present, although the SOEC has significant energy efficiency advantages, its promotion and application still face multiple constraints, i.e., gradual decay of oxygen electrodes under high temperature and high vapor partial pressure, mechanical and electrochemical damage caused by power fluctuations, and daunting initial capital investment. Subsequent exploration should focus on preparing new electrode materials with a higher stability, establishing flexible thermoelectric synergistic regulation mechanisms to adapt to fluctuating renewable energy, and promoting standardization and cost reduction and efficiency improvement throughout entire industry chain. The cost of photovoltaic and wind power continues to decrease, coupled with increasing demand for green hydrogen in chemical and metallurgical fields. Solid oxide electrolysis cell technology is expected to be widely applied in "electricity hydrogen ammonia/methanol" integrated system, distributed energy system, and sustainable refining scenarios. This technology will undoubtedly become a key pillar technology supporting the dual carbon goals in China.

Cement production accounts for approximately 12% of China's total CO₂ emissions, having a significant challenge to achieving the national "dual carbon goals". Carbon capture, utilization, and storage (CCUS) represent a pivotal innovative technology for mitigating these emissions. However, conventional amine-based CO₂ capture requires an energy-intensive high-temperature desorption, hindering its industrial implementation in cement plants. Also, the limited utilization pathways for captured CO₂ pose another challenge for cement CCUS. Diethanolamine (DEA) offers a promising solution as it functions both as a CO₂ absorber and a cement additive. This dual capability enables a potential carbonation utilization of CO₂ absorbed DEA solutions without requiring the desorption step within cementitious systems. This study was thus to investigate the effect of CO₂-absorbed diethanolamine (DEAC) on the early hydration behavior and strength development of cementitious systems. The findings could propose a novel approach for low-energy CO₂ capture coupled with efficient in-situ utilization within cement industry.

Cement mortars with a water-to-cement ratio (W/C) of 0.50 were prepared with P·I 42.5 Portland cement (GB 8076) and ISO standard sand. The specimens were designated as REF, D0.1%C0%, D0.1%C0.02%, D1.0%C0%, and D1.0%C0.22%, respectively. DEA and its equivalent CO₂ admixture were added as percentages of cement mass. All associated cement paste mixtures were prepared at a W/C ratio of 0.3. DEAC was prepared by continuously bubbling CO₂ gas (≥99% purity) at a flow rate of 200 mL/min through a 5 mol/L DEA solution maintained at 40 ℃ until saturation was achieved. An eight-channel microcalorimeter recorded the hydration heat of cement paste specimens at 25 ℃ for 72 h. The phase composition of hardened cement pastes was determined by X-ray diffraction (XRD). The contents of bound water, CH, and CaCO₃ were analyzed by thermogravimetric analysis (TGA). The cumulative porosity and pore size distribution of hardened paste samples at 7 d were characterized by mercury intrusion porosimetry (MIP). The compressive strength was measured on mortar specimens at 1, 3 d and 7 d of curing in accordance with the standard GB/T 17671.

The hydration calorimetry results demonstrate that D0.1%C0.02% and D0.1%C0% both accelerate the hydration rate of silicate phases, as evidenced by an increased second exothermic peak rate, while leaving the induction period duration unaffected. Conversely, D1.0%C0% and D1.0%C0.22% significantly reduce the second exothermic peak rate. D1.0%C0.22% extends the hydration induction period to 240 min, while D1.0%C0% has a negligible effect on its duration. The XRD patterns and TG analyses reveal that the impact of DEAC on the cement hydration depends critically on its specific DEA and CO₂ dosage. At a low dosage (i.e., D0.1%C0.02%), a mild carbonation promotes a concurrent hydration of silicate and aluminate phases. However, a high dosage (i.e., D1.0%C0.22%) substantially inhibits early hydration of silicates. The MIP results indicate that DEAC and DEA both refine the pore structure of hardened cement paste. The pores below 20 nm are significantly reduced in D0.1%C0% and D0.1%C0.02% systems, aligning with their enhanced early hydration kinetics. This refinement also occurres in D1.0%C0% and D1.0%C0.22% systems despite inhibited silicate hydration. The results of compressive strength tests show that D0.1%C0.02% and D0.1%C0% can enhance mortar strengths at 1, 3 d, and 7 d, respectley. The strengths of D0.1%C0.02% systems can be increased by 8.4%, 10.2%, and 16.8% at these ages, respectively, primarily due to the DEA component with the weak carbonation contributing minimal additional enhancement. The 3-day and 7-day strengths of D1.0%C0.22% and D1.0%C0% systems both are increased (more significantly in the carbonated system), indicating a synergistic hydration-carbonation effect. However, the 1-day strength of D1.0%C0.22% system drastically is reduced by 52.2%, with silicates hydration inhibition by D1.0%C0% identified as a primary factor underpinning early strength reduction. According to the analysis of bound water content, calcium hydroxide (CH) content, porosity, and compressive strength relationships, a linear correlation between CH content and mortar strength is proposed. This demonstrates that silicate phase hydration kinetics can be modulated differently by DEAC and DEA formulations-fundamentally governed compressive strength development.

The addition of 0.1%DEA with 0.02% CO₂ (D0.1%C0.02%) as DEAC enhanced the flexural and compressive strengths of cement mortar at 1, 3 d, and 7 d. In contrast, the addition of 1.0% DEA with 0.22% CO₂ (D1.0%C0.22%) significantly reduced the 1-day strength. In D0.1%C0.02% system, the CO₂ component reacted with dissolved Ca²⁺ released from cement minerals to precipitate CaCO₃. This reaction promoted cement hydration, refined the pore structure of the hardened paste by reducing the volume of harmful pores, and facilitated a synergistic enhancement of hydration and carbonation. D1.0%C0.22% addition significantly retarded cement hydration within the first 24 h, primarily by inhibiting the dissolution of silicate phases and extending the induction period, leading to the reduced early strength. Although carbonation exacerbated the retardation of silicate phase hydration via DEA interaction, the hydration process recovered normal kinetics after 7 d.