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The bulk photovoltaic (BPV) effect of conventional ferroelectric (FE) materials has sparked a great deal of interest due to anomalous above-bandgap photovoltage. However, large bandgaps and weak photocurrents remain longstanding challenges for FE PV materials in practical applications. To address these issues, we propose a new defect-engineering strategy and demonstrate it on a narrow bandgap centrosymmetric material, BiNbO4 (BNO): the BPV effect is introduced into BNO by tuning the defect amounts, then a defect-modified homojunction structure is constructed to enhance the BPV effect. This defect engineering strategy enables synergetic effects, e.g., enhanced light absorption, FE-like depolarization field and interfacial polarization. This homojunction structure results in two-fold promotion of photovoltage and ten-fold promotion of photocurrent, compared to the defect-modified BNO sample. We believe this new strategy will break through limitations in traditional material design and pave a novel route to future multifunctional materials, especially high performance BPV materials. [ABSTRACT FROM AUTHOR]

Local defect structures play significant roles on material properties, but they are seriously neglected in the design, synthesis, and development of highly efficient TiO2‐based visible light catalysts (VLCs). Here, we take anatase TiO2 nanocrystals that contain (Ti3+, N3−) ions and have the complicated chemical formula of (Ti1-x4+Tix3+)(O2-y-z2-Ny3- □z) as an example, and point out that the formation of Ti3+‐VO‐2Ti4+‐N3− local defect clusters is a key missing step for significantly enhancing VLC properties of host TiO2 nanocrystals. Experimental and theoretical investigations also demonstrate the emergent behaviors of these intentionally introduced defect clusters for developing highly efficient VLCs. This research thus not only provides highly efficient visible light catalysts for various practical applications but also addresses the significance of local defect structures on modifying material properties. Defect‐clusters‐driven: Local defect structure could determine or create material properties since it could change a local chemical environment and subsequently mediate the electronic state density of materials. Here, we demonstrate that the deliberate design and formation of Ti3+‐VO‐2Ti4+‐N3− defect clusters in TiO2 anatase nanocrystals would drive the highly efficient visible light catalytic decomposition of organic contaminates. This research thus not only presents a defect‐engineering route to design/develop highly efficient visible light catalysts but also highlights the significance of local defect structures on modifying material properties. [ABSTRACT FROM AUTHOR]

Defect sites present on the surface of catalysts serve a crucial role in different catalytic processes. Herein, we have investigated defect engineering within a hybrid system composed of "soft" polymer catalysts and "hard" metal nanoparticles, employing the disparity in their thermal expansions. Electron paramagnetic resonance, X-ray photoelectron spectroscopy, and mechanistic studies together reveal the formation of new abundant defects and their synergistic integrability with plasmonic enhancement within the hybrid catalyst. These active defects, co-localized with plasmonic Ag nanoparticles, promote the utilization efficiency of hot electrons generated by local plasmons, thereby enhancing the CO 2 photoreduction activity while maintaining the high catalytic selectivity.

Oxygen vacancies in inorganic semiconductors play an important role in reducing electron-hole recombination, which may have important implications in photocatalysis. Cuprous oxide (Cu2O), a visible light active p-type semiconductor, is a promising photocatalyst. However, the synthesis of photostable Cu2O enriched with oxygen defects remains a challenge. We report a simple method for the gram-scale synthesis of highly photostable Cu2O nanoparticles by the hydrolysis of a Cu(i)-triethylamine [Cu(i)-TEA] complex at low temperature. The oxygen vacancies in these Cu2O nanoparticles led to a significant increase in the lifetimes of photogenerated charge carriers upon excitation with visible light. This, in combination with a suitable energy band structure, allowed Cu2O nanoparticles to exhibit outstanding photoactivity in visible light through the generation of electron-mediated hydroxyl (OH˙) radicals. This study highlights the significance of oxygen defects in enhancing the photocatalytic performance of promising semiconductor photocatalysts.