Chen Huayu, Song Lizhu, Ouyang Shuxin, Wang Jianbo, Lv Jun, Ye Jinhua
TJU-NIMS International Collaboration Laboratory School of Materials Science and Engineering Tianjin University Tianjin 300072 China.
College of Chemistry Central China Normal University Wuhan 430079 China.
Adv Sci (Weinh). 2019 Jul 11;6(16):1900465. doi: 10.1002/advs.201900465. eCollection 2019 Aug 21.
Oxygen evolution electrode is a crucial component of efficient photovoltaic-water electrolysis systems. Previous work focuses mainly on the effect of electronic structure modulation on the oxygen evolution reaction (OER) performance of 3d-transition-metal-based electrocatalyst. However, high-atomic-number W-based compound with complex electronic structure for versatile modulation is seldom explored because of its instability in OER-favorable alkaline solution. Here, codoping induced electronic structure modulation generates a beneficial effect of transforming the alkaline-labile WO (WO) in to efficient alkaline-solution-stable Co and Fe codoped WO (Co&Fe-WO) with porous urchin-like structure. The codoping lowers the chemical valence of W to ensure the durability of W-based catalyst, improves the electron-withdrawing capability of W and O to stabilize the Co and Fe in OER-favorable high valence state, and enriches the surface hydroxyls, which act as reactive sites. The Co&Fe-WO shows ultralow overpotential (226 mV, = 10 mA cm), low Tafel slope (33.7 mV dec), and good conductivity. This catalyst is finally applied to a photovoltaic-water splitting system to stably produce hydrogen for 50 h at a high solar-to-hydrogen efficiency of 16.9%. This work highlights the impressive effect of electronic structure modulation on W-based catalyst, and may inspire the modification of potential but unstable catalyst for solar energy conversion.
析氧电极是高效光伏 - 水电解系统的关键组件。以往的工作主要集中在电子结构调制对基于3d过渡金属的电催化剂析氧反应（OER）性能的影响上。然而，由于其在有利于OER的碱性溶液中不稳定，具有复杂电子结构可进行多种调制的高原子序数W基化合物很少被研究。在此，共掺杂诱导的电子结构调制产生了有益效果，即将碱性不稳定的WO（WO）转变为具有多孔海胆状结构的高效碱性溶液稳定的Co和Fe共掺杂WO（Co&Fe - WO）。共掺杂降低了W的化学价以确保W基催化剂的耐久性，提高了W和O的吸电子能力，使Co和Fe在有利于OER的高价态下稳定，并丰富了作为反应位点的表面羟基。Co&Fe - WO表现出超低过电位（226 mV，= 10 mA cm）、低塔菲尔斜率（33.7 mV dec）和良好的导电性。该催化剂最终应用于光伏 - 水分解系统，以16.9%的高太阳能到氢能效率稳定产氢50小时。这项工作突出了电子结构调制对W基催化剂的显著影响，并可能激发对潜在但不稳定的太阳能转换催化剂进行改性。
