Jeon Tae Hwa, Monllor-Satoca Damián, Moon Gun-Hee, Kim Wooyul, Kim Hyoung-Il, Bahnemann Detlef W, Park Hyunwoong, Choi Wonyong
Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.
Department of Analytical and Applied Chemistry, Institut Químic de Sarrià (IQS)-School of Engineering, Universitat Ra-mon Llull, Via Augusta, 390, 08017, Barcelona, Spain.
Nat Commun. 2020 Feb 19;11(1):967. doi: 10.1038/s41467-020-14775-2.
Ag(I) is commonly employed as an electron scavenger to promote water oxidation. In addition to its straightforward role as an electron acceptor, Ag(I) can also capture holes to generate the high-valent silver species. Herein, we demonstrate photoelectrocatalytic (PEC) water oxidation and concurrent dioxygen evolution by the silver redox cycle where Ag(I) acts as a hole-transfer mediator. Ag(I) enhances the PEC performance of WO electrodes at 1.23 V vs. RHE with increasing O evolution, while forming Ag(II) complexes (AgNO). Upon turning off both light and potential bias, the photocurrent immediately drops to zero, whereas O evolution continues over ~10 h with gradual bleaching of the colored complexes. This phenomenon is observed neither in the Ag(I)-free PEC reactions nor in the photocatalytic (i.e., bias-free) reactions with Ag(I). This study finds that the role of Ag(I) is not limited as an electron scavenger and calls for more thorough studies on the effect of Ag(I).
银（I）通常用作电子清除剂以促进水氧化。除了作为电子受体的直接作用外，银（I）还可以捕获空穴以生成高价银物种。在此，我们展示了通过银氧化还原循环进行的光电催化（PEC）水氧化和同时的氧气析出，其中银（I）充当空穴转移介质。随着析氧增加，银（I）在相对于可逆氢电极（RHE）为1.23 V时提高了WO电极的PEC性能，同时形成银（II）配合物（AgNO）。关闭光和电势偏压后，光电流立即降至零，而析氧在约10小时内持续，有色配合物逐渐褪色。在无银（I）的PEC反应中以及在有银（I）的光催化（即无偏压）反应中均未观察到这种现象。本研究发现银（I）的作用不限于作为电子清除剂，并呼吁对银（I）的影响进行更深入的研究。
