Graphical Advanced ZnO/ZnCr 2 O 4 photocatalysts derived from ZnCr-layered double hydroxide (ZnCr-LDH) precursors are successfully synthetized by a simple thermal process. The optimized ZnO/ZnCr 2 O 4 exhibit a considerable ammonia photosynthesis rate of 31.7 μmol g −1 h −1 in pure water, with the origin of the high activity being derived from the high-efficiency carrier separation due to the abundant interfaces. Drawing inspiration from the enzyme nitrogenase in nature, researchers are increasingly delving into semiconductor photocatalytic nitrogen fixation due to its similar surface catalytic processes. Herein, we reported a facile and efficient approach to achieving the regulation of ZnO/ZnCr 2 O 4 photocatalysts with ZnCr-layered double hydroxide (ZnCr-LDH) as precursors. By optimizing the composition ratio of Zn/Cr in ZnCr-LDH to tune interfaces, we can achieve an enhanced nitrogen photofixation performance (an ammonia evolution rate of 31.7 μmol g −1 h −1 using pure water as a proton source) under ambient conditions. Further, photo-electrochemical measurements and transient surface photovoltage spectroscopy revealed that the enhanced photocatalytic activity can be ascribed to the effective carrier separation efficiency, originating from the abundant composite interfaces. This work further demonstrated a promising and viable strategy for the synthesis of nanocomposite photocatalysts for nitrogen photofixation and other challenging photocatalytic reactions.
Liyan Wang,Xiaojun Yang,Yuhang Tan,Yu Li,Zhipeng Wang,Jian Song
Due to the complicated component of ZnCr oxides, the function of the active phases remains controversy, limiting its improvement of catalytic performance for converting syngas to higher alcohols. Herein, a series of ZnCr catalysts with tunable ZnO/ZnCr 2 O 4 molar ratios were fabricated via ball milling of the two individual oxides. Within the ZnO:ZnCr 2 O 4 range of 1:1 to 0.5:1, both CO conversion (18.5%) and isobutanol selectivity (29.0%) were significantly enhanced, while the water‑gas shift reaction and hydrocarbon formation were effectively suppressed. This improved performance originated from synergistic interface effects as revealed by the systematic characterization (XPS, CO‑TPD, and in situ DRIFTS etc.). Lattice distortion and electronic interaction at the interface induced the producing of octahedrally coordinated Zn 2+ sites on ZnCr 2 O 4 , strengthening CO adsorption, meanwhile, ZnO promoted interface hydrogen migration and hydroxyl cycling, steering the CHO* intermediate formation and facilitating C–C coupling. Furthermore, the electron‑rich lattice oxygen at the interface, with moderate basicity, served as active sites for β addition reaction of C 2 intermediate and carbon‑chain growth. These findings clarify the critical role of dual‑phase interface structure in regulating the reaction pathway during syngas conversion, providing a new strategy for the design of high‑performance catalysts for isobutanol synthesis.
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