Crystal structure prediction is a powerful theoretical simulation tool, which can determine the crystal structure of materials with the given information of chemical composition. However, its application is severely limited due to the highly computational cost. In recent years, the state-of-art machine learning methods reveal a promising prospect in accelerating the conventional scientific computing, thus introducing the methods into the crystal structure prediction. This review briefly introduced recent progress on the application of machine learning for the crystal structure prediction. Two aspects were discussed, i.e., accelerating the energy evaluation and enhancing the potential energy surface sampling. In addition, some insights into the future development in this aspect were also suggested.

Several exfoliation methods including thermal treatment in air and hydrogen, ultrasonication, and chemical treatment with sodium borohydride were applied to modify the properties of bulk graphitic carbon nitride (g-CN). The prepared samples were characterized by X-ray diffraction, X-ray photoemission spectroscopy, Fourier transform infrared spectroscopy, UV-Vis diffuse reflectance spectroscope and N₂ physisorption, and their photocatalytic performances were evaluated via the degradation of organic pollutants in aqueous solution. The results indicated that the exfoliation methods affect greatly on the physicochemical and photocatalytic properties of g-CN, and the optimum sample can be obtained by thermal treating in air (g-CN_A), showing 99.87% conversion at 40 min for the photocatalytic degradation of tetracycline hydrochloride, and the performance was preserved even after four cycles. The mechanism on the reaction intermediates with trapping experiments indicated that superoxide anion radicals (·O₂^-) are the main active species of the reaction.

Photocatalytic reactions can convert solar energy into storable chemical energy, thus providing a feasible strategy for solving energy crisis and environmental problems. However, the photochemical conversion efficiency is restricted due to the low transfer and separation efficiency of photogenerated carriers. The emerging S-scheme heterojunction photocatalysts have attracted recent attention in the fields of solar fuel conversion and environmental purification for the spatially efficient separation of photogenerated carriers and strong redox ability. This review represented recent development on the design principles, charge transfer mechanism and applications of S-scheme heterojunction photocatalysts. In addition, their prospects and challenges were also discussed.

Electrolysis of water to produce hydrogen is a promising green method to achieve sustainable energy supply. A NiCuP foam nickel hydrogen precipitation electrocatalyst was prepared by one-step hydrothermal method. The results show that the electrocatalyst has a good hydrogen reaction activity at 12 h at the nickel-copper ratio of 8∶1 and the hydrothermal temperature of 140 ℃. The effect of modifier on the catalytic activity was also investigated. It is indicated that the addition of the modifier NaCl can provide a better ion interaction environment, thus significantly improving the catalytic performance. At a current density of 10 mA/cm², the overpotential is 108 mV with a Tafel slope of 113 mV/dec (the overpotential change is 113 mV for every 10-fold change in current). The calculations show that the atomic d-p orbital interaction of Ni₂P-Cu₃P induces an enhancement of the electronic activity at the catalyst interface, thus reducing the activation barrier. Moreover, the addition of NaCl promotes the dissociation of H₂O molecules into H ions, thus enhancing the catalytic activity of hydrogen evolution reaction. This work provides a research basis for the research and development of transition metal electrocatalysts.

The formation and directional arrangement of silver halide nanorods in glass and their influences on the polarization properties were investigated. The results show that silver halide particles are easier to precipitate in a sodium boron rich phase. The optimum heat treatment condition for the crystallization is at 615 ℃ for holding time of 12 h. The formation and orientation of silver halide nanorods in glass is a winning combination of glass stretching temperature, stress and speed. The average diameter of AgCl nanorods in glass is 98 nm, the average length is 558 nm, the average aspect ratio of the nanorods is 1∶5.6, and the nanorods are oriented along the stretching direction of glass when the stretching temperature is 570 ℃, the stress is 735 N, and the speed is 120 mm/min. According to the polarizing property of glass after high-pressure reduction, the more AgCl nanorods in the unit area of the stretched glass surface is, the higher the extinction ratio of the reduced glass will be.

Waste lithium batteries have become a research hotspot due to their extremely high resources and hazards. Hygrometallurgical recycling is the main existing method for processing waste lithium battery cathode materials, and the recovery of valuable metal elements from the leaching solutions is the key to hygrometallurgical recovery of waste cathode materials. In this paper, nickel, cobalt and manganese were precipitated from a malic acid leaching solution of high manganese cathode material of waste lithium battery as raw material via ozone oxidation, and the optimal precipitation conditions were obtained. The results show that the precipitation rates of nickel, cobalt, and manganese are 18.2%, 41.5%, and 85.8%, and the contents of nickel, cobalt, and manganese in the ozone precipitation slag are 0.85%, 1.63%, and 41.3%, respectively under the optimal precipitation conditions. The ozone oxidation precipitation slag is a high manganese-based precursor, and the precursor is regenerated into LiMn₂O₄ cathode material after supplementing lithium. The first discharge specific capacity of this regenerate cathode material is 95.4 mA·h/g, and the first charge-discharge efficiency is 84%. The discharge specific capacity retention rate is 67.4% at a high rate, and the discharge specific capacity retention rate after 100 cycles is 80%.

A phononic crystal coupled with the acoustic black hole structure was proposed based on the local resonance theory. The low frequency band gap was widened by utilizing the low frequency, broad band gap, and multi-modal properties of the acoustic black hole structure. The energy band structure, eigenmodes and attenuation characteristics of the phononic crystal were calculated by the finite element method. The generation mechanism of its band gap was analyzed, and the influence of the geometric parameters (i.e., the structural parameters of the acoustic black hole) on the band gap was discussed. The results show that the phononic crystal has multiple band gaps at 1 600 Hz, and the first complete band gap ranges from 12 to 805 Hz. The band gap coverage below 40 Hz is 70%, and the band gap coverage within 1 600 Hz reaches 97.3%. The starting and cut-off frequencies of the first complete band gap are mainly determined by the vibrational modes of the scatterer and the acoustic black hole structure. The starting frequency of the first complete band gap increases with increasing the height of the acoustic black hole structure short side. The width and short side height of the acoustic black hole structure and the height of the short plate have an effect on the cut-off frequency and the width of the first complete band gap.

Graphdiyne (GD) is one of carbon allotropes with the unique structure and has ideal high strength, excellent light transmittance, electrical conductivity, high carrier mobility, and thermal conductivity. GD with a natural band gap is an intrinsic semiconductor with special charge transport properties. GD shows a band gap in the range of 0.45 to 1.30 eV, compared with graphene without band gap, which has a promising potential for electronic, catalytic, optical and mechanical applications. Also, GD has two different Dirac cones near the top and bottom of the Fermi energy level, indicating that GD is a self-doped semiconductor with charge carriers and does not require additional doping like graphene. GD can be used as a potential and excellent photocatalytic material, and theoretically it is needed to be modified to build active sites for efficient photo-induced reactions.

High-entropy oxides (HEO) are a novel material with the unique electrochemical properties, which are stabilized due to the high configurational entropy. In this paper, a high-entropy (Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O nanopowder with the sizes of 40-65 nm and a rocksalt structure was synthesized by a polyacrylamide gel method and subsequent calcination at 900 ℃ for 2 h in the presence of a mole ratio of acrylamide/metal cations of 120∶1. The results show that the temperature of forming a single-phase (Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O nanopowder decreases with the increase of the mole ratio of acrylamide/metal cations. The HEO nanopowder has a specific capacitance of 402 F/g at a current density of 1 A/g. A rate capability of 62% appears at 20 A/g. The capacitance retention is 61% after 2 000 cycles at a current density of 5 A/g. It is indicted that (Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)O nanopowder could be used as a prospective electrode material for supercapacitors.

In this work, for exploring the controlled growth strategy of indium-oxide-based semiconductor film with preferred orientation and investigating the effect of crystal orientation on the photoelectric property, nitrogen-doped indium oxide (In₂O₃:N) films with (222) and (440) preferred orientation were prepared on quartz (SiO₂) substrate by magnetron sputtering, respectively. The crystal structure, surface morphology, elemental composition and optical bandgap of In₂O₃:N films were characterized by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy and ultraviolet-visible spectrophotometer, respectively. The photoelectric properties of as-grown films with different preferred orientation were investigated. The results show that the nitrogen doping in In₂O₃:N films with different preferred orientation mainly is dominated by nitrogen substitutional oxygen. The band gap of indium oxide can be reduced to 2.89 eV by nitrogen doping. The In₂O₃:N film with (440) preferred orientation has a shorter photoresponse time than the (222) one.