Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, 1301 Beal Avenue, Ann Arbor, Michigan 48109, United States.
Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
Nano Lett. 2022 Mar 23;22(6):2236-2243. doi: 10.1021/acs.nanolett.1c04220. Epub 2022 Mar 8.
Tuning the surface structure of the photoelectrode provides one of the most effective ways to address the critical challenges in artificial photosynthesis, such as efficiency, stability, and product selectivity, for which gallium nitride (GaN) nanowires have shown great promise. In the GaN wurtzite crystal structure, polar, semipolar, and nonpolar planes coexist and exhibit very different structural, electronic, and chemical properties. Here, through a comprehensive study of the photoelectrochemical performance of GaN photocathodes in the form of films and nanowires with controlled surface polarities we show that significant photoelectrochemical activity can be observed when the nonpolar surfaces are exposed in the electrolyte, whereas little or no activity is measured from the GaN polar -plane surfaces. The atomic origin of this fundamental difference is further revealed through density functional theory calculations. This study provides guideline on crystal facet engineering of metal-nitride photo(electro)catalysts for a broad range of artificial photosynthesis chemical reactions.
调整光电 极的表面结构为人工光合作用中面临的一些关键挑战提供了有效的解决方法，如效率、稳定性和产物选择性，而氮化镓（GaN）纳米线在这些方面表现出巨大的潜力。在 GaN 纤锌矿晶体结构中，极性、半极性和非极性平面共存，并表现出非常不同的结构、电子和化学性质。在这里，我们通过对具有受控表面极性的薄膜和纳米线形式的 GaN 光电阴极的光电化学性能进行全面研究表明，当暴露在电解质中非极性表面时可以观察到显著的光电化学活性，而从 GaN 极性平面表面测量到的活性则很小或没有。通过密度泛函理论计算进一步揭示了这种基本差异的原子起源。这项研究为金属-氮化物光（电）催化剂的晶面工程提供了指导，以应用于广泛的人工光合作用化学反应。
