Yin Jie, Di Fangfang, Guo Junxue, Zhang Kaixuan, Xu Wenli, Wang Yunying, Shi Shaozhen, Chai Ning, Chu Chaofan, Wei Jiazhen, Li Wenzhi, Shao Xin, Pu Xipeng, Zhang Dafeng, Ren Xiaozhen, Wang Jie, Zhao Jinsheng, Zhang Xianxi, Wei Xinting, Wang Fang, Zhou Huawei
College of Materials Science and Engineering, School of Chemistry and Chemical Engineering, Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, Liaocheng University, No. 1 Hunan Road, Liaocheng, Shandong 252059, China.
Changzhou Vocational Institute of Engineering, Changzhou, Jiangsu 213000, China.
ACS Omega. 2018 Sep 11;3(9):11009-11017. doi: 10.1021/acsomega.8b01143. eCollection 2018 Sep 30.
Splitting of water into hydrogen and oxygen has become a strategic research topic. In the two semi-reactions of water splitting, water oxidation is preferred to the four-electron-transfer process with a higher overpotential (η) and is the decisive step in water splitting. Therefore, efficient water oxidation catalysts must be developed. IrO and RuO catalysts are currently the most efficient catalysts in water oxidation. However, the limited reserve and high prices of precious metals, such as Ir and Ru, limit future large-scale industrial production of water oxidation catalysts. In this study, we tune inert Ni-foam into highly active NiOOH/FeOOH heterostructures as water oxidation catalysts via three-step strategy (surface acid-treating, electroplating, and electrooxidation). NiOOH/FeOOH heterostructures as water oxidation catalysts only require η of 257 mV to reach a current density of 10 mA cm, which is superior to that of IrO/Ni-foam (280 mV). The high electrochemically active surface area (72.50 cm) and roughness factor demonstrate abundant interfaces in NiOOH/FeOOH heterostructures, thus accelerating water oxidation activity. The small value (4.8 Ω cm) of charge transfer resistance ( ) indicate that fast electronic exchange occurs between NiOOH/FeOOH heterostructures catalyst and reaction of water oxidation. Hydrogen-to-oxygen volume ratios (approximately 2:1) indicate an almost overall water splitting by the double-electrode system. Faraday efficiency of H or O is close to 90% at 2:1 hydrogen-to-oxygen volume ratio. NiOOH/FeOOH heterostructures exhibit good stability. The results provide significance in fundamental research and practical applications in solar water splitting, artificial photoelectrochemical cells, and electrocatalysts.
将水分解为氢气和氧气已成为一个具有战略意义的研究课题。在水分解的两个半反应中，水氧化倾向于进行四电子转移过程，具有较高的过电位（η），并且是水分解的决定性步骤。因此，必须开发高效的水氧化催化剂。IrO 和 RuO 催化剂目前是水氧化中最有效的催化剂。然而，铱（Ir）和钌（Ru）等贵金属储备有限且价格高昂，限制了水氧化催化剂未来的大规模工业化生产。在本研究中，我们通过三步策略（表面酸处理、电镀和电氧化）将惰性泡沫镍调制成高活性的 NiOOH/FeOOH 异质结构作为水氧化催化剂。作为水氧化催化剂的 NiOOH/FeOOH 异质结构仅需 257 mV 的过电位即可达到 10 mA cm 的电流密度，优于 IrO/泡沫镍（280 mV）。高电化学活性表面积（72.50 cm）和粗糙度因子表明 NiOOH/FeOOH 异质结构中存在丰富的界面，从而加速了水氧化活性。电荷转移电阻（ ）的小值（4.8 Ω cm）表明 NiOOH/FeOOH 异质结构催化剂与水氧化反应之间发生了快速的电子交换。氢氧体积比（约为 2:1）表明双电极系统几乎实现了整体水分解。在氢氧体积比为 2:1 时，H 或 O 的法拉第效率接近 90%。NiOOH/FeOOH 异质结构表现出良好的稳定性。这些结果在太阳能水分解、人工光电化学电池和电催化剂的基础研究和实际应用中具有重要意义。
