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The synergistic effect of surface oxygen vacancy with induced lattice strains on visible light-driven photocatalytic H2evolution over black TiO2was investigated. Experimental measurements and theoretical calculations on the lattice parameters of black TiO2show that surface oxygen vacancies induce internal lattice strain during two-step aluminothermic reduction, which regulates the band structure and optimizes the photoinduced charge behavior of black TiO2. The hydrogen evolution rate of black TiO2with strain modification shows a 12-fold increase to 1.882 mmol/g· h (equal to 4.705 μmol/cm2·h) under visible light illumination. The metastable state caused by the surface oxygen vacancies leads to the formation of a high-energy surface, which enhances visible light absorption and improves the photoinduced charge separation efficiency. Furthermore, the internal lattice strain provides the driving force and channel for the directional movement of photoinduced electrons from the bulk to the high-energy surface for photocatalytic H2evolution. This strategy provides a new method for designing a high-performance photocatalyst for H2production.

Ni-rich LiNi0.8Co0.1Mn0.1O2(NCM811) cathode is considered to be among the most promising candidates for high-energy-density lithium-ion batteries (LIBs). However, both capacity fading and structural degradation occur during long-term cycling, which extremely limit the commercial applications of NCM811, especially at a high cutoff voltage (>4.3 V). Here, we design a double-shell hybrid nanostructure consisting of a Li2SiO3coating layer and a cation-mixed layer (Fm3̅mphase) to improve its electrochemical performance. Consequently, the Si-modified NCM811 electrode shows outstanding cycling stability with a 95.2% capacity retention at 4.3 V after 100 cycles and 87.3% at a 4.5 V high cutoff voltage after 100 cycles. This designed double-shell hybrid nanostructure alleviates side reactions, structural degradation, and internal cracking, effectively enhancing the surface structural stability. This efficient strategy provides a valuable step toward further commercial applications of the LiNi0.8Co0.1Mn0.1O2cathode and enriches the fundamental understanding of layered cathode materials.

SiOx-based anode materials with high capacity and outstanding cycling performance have gained numerous attentions. Nevertheless, the poor electrical conductivity and non-negligible volume change hinder their further application in Li-ion batteries. Herein, we propose a new strategy to construct a hollow nanosphere with boron-doped Si/SiOxdecorated with vanadium nitride (VN) nanoparticles and embedded in a nitrogen-doped, porous, and partial graphitization carbon layer (B-Si/SiOx@VN/PC). Benefiting from such structural and compositional features, the B-Si/SiOx@VN/PC electrode exhibits a stable cycling capacity of 1237.1 mA h g–1at a current density of 0.5 A g–1with an appealing capacity retention of 87.0% after 300 cycles. Additionally, it delivers high-rate capabilities of 1139.4, 940.7, and 653.4 mA h g–1at current densities of 2, 5, and 10 A g–1, respectively, and ranks among the best SiOx-based anode materials. The outstanding electrochemical performance can be ascribed to the following reasons: (1) its hollow structure makes the Li+transportation length decreased. (2) The existing nanopores facilitate the Li+insertion/desertion and accommodate the volume variation. (3) The nitrogen-doped partial graphitization carbon enhances the electrical conductivity and promotes the formation of stable solid electrolyte interface layers during the repetitive Li+intercalation/extraction process.