Fan Guozheng, Fang Tao, Wang Xin, Zhu Yaodong, Fu Hongwei, Feng Jianyong, Li Zhaosheng, Zou Zhigang
Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, P. R. China.
Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, P. R. China; Jiangsu Key Laboratory for Nano Technology, Nanjing University, Nanjing 210093, P. R. China.
iScience. 2019 Mar 29;13:432-439. doi: 10.1016/j.isci.2019.02.024. Epub 2019 Mar 1.
TaN, as a fascinating photoanode for solar hydrogen production, is expected to split water without any bias, because its band edge potentials straddle HO redox potentials. Unfortunately, TaN photoanodes can split water only when a bias of at least 0.6-0.9 V is applied. It means that they exhibit an onset potential as high as 0.6-0.9 V (reversible hydrogen electrode). In this study, density functional theory calculations show that the band edge potentials of TaN have a shift of approximately -0.42 eV relative to vacuum level when exposed to water. The increased ratio of dissociated water at TaN-water interface will further make the band edge potentials shift -0.85 eV relative to vacuum level, implying the anodic shifts of the onset potential for water oxidation. The findings may reveal the mystery of the unexpectedly high onset potential of TaN, as high as 0.6-0.9 V.
氮化钽作为一种用于太阳能制氢的迷人光阳极，有望在无任何偏压的情况下分解水，因为其能带边缘电位跨越了水的氧化还原电位。不幸的是，氮化钽光阳极只有在施加至少0.6 - 0.9 V的偏压时才能分解水。这意味着它们表现出高达0.6 - 0.9 V（可逆氢电极）的起始电位。在本研究中，密度泛函理论计算表明，氮化钽的能带边缘电位在暴露于水时相对于真空能级有大约-0.42 eV的偏移。氮化钽-水界面处离解水比例的增加将进一步使能带边缘电位相对于真空能级偏移-0.85 eV，这意味着水氧化起始电位的阳极偏移。这些发现可能揭示了氮化钽起始电位高达0.6 - 0.9 V这一意外之高的奥秘。
