Wang Ya, Yu Jun, Wang Yanding, Chen Zhuwen, Dong Lei, Cai Rongming, Hong Mei, Long Xia, Yang Shihe
State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Nano-Micro Materials Research, School of Chemical Biology & Biotechnology, Peking University Shenzhen Graduate School (PKUSZ) Shenzhen 518055 P. R. China
RSC Adv. 2020 Jun 18;10(39):23321-23330. doi: 10.1039/d0ra03111a. eCollection 2020 Jun 16.
Low-cost and efficient electrocatalysts with high dispersion of active sites and high conductivity are of high importance for oxygen evolution reaction (OER). Herein, we use amorphous mesoporous fumed silica (MFS) as a skeleton material to disperse Ni and Fe through a simple impregnation strategy. The MFS is etched away during the OER process in 1 M KOH to prepare a stable mesoporous Ni-Fe electrocatalyst. The high specific surface area and abundant surface silanol groups in the mesoporous fumed silica afford rich anchor sites for fixing metal atoms strong chemical metal-oxygen interactions. Raman and XPS investigations reveal that Ni formed covalent bonds with surface Si-OH groups, and Fe inserted into the framework of fumed silica forming Fe-O-Si bonds. The mesoporous Ni-Fe catalysts offer high charge transfer abilities in the OER process. When loaded on nickel foam, the optimal 2Ni1Fe-MFS catalyst exhibits an overpotential of 270 mV at 10 mA cm and a Tafel slope of 41 mV dec. Notably, 2Ni1Fe-MFS shows a turnover frequency value of 0.155 s at an overpotential of 300 mV, which is 80 and 190 times higher than that of the state-of-the-art IrO and RuO catalysts. Furthermore, 2Ni1Fe-MFS exhibits 100% faradaic efficiency, large electrochemically active surface area, and good long-term durability, confirming its outstanding OER performance. Such high OER efficiency can be ascribed to the synergistic effect of high surface area, dense metal active sites and interfacial conductive path. This work provides a promising strategy to develop simple, cost-effective, and highly efficient porous Ni-Fe based catalysts for OER.
具有高活性位点分散度和高导电性的低成本高效电催化剂对于析氧反应（OER）至关重要。在此，我们使用无定形介孔气相二氧化硅（MFS）作为骨架材料，通过简单的浸渍策略分散Ni和Fe。在1 M KOH的OER过程中，MFS被蚀刻掉，以制备稳定的介孔Ni-Fe电催化剂。介孔气相二氧化硅中的高比表面积和丰富的表面硅醇基团为固定金属原子提供了丰富的锚定位点以及强大的化学金属-氧相互作用。拉曼和XPS研究表明，Ni与表面Si-OH基团形成共价键，Fe插入气相二氧化硅骨架形成Fe-O-Si键。介孔Ni-Fe催化剂在OER过程中具有高电荷转移能力。当负载在泡沫镍上时，最佳的2Ni1Fe-MFS催化剂在10 mA cm时的过电位为270 mV，塔菲尔斜率为41 mV dec。值得注意的是，2Ni1Fe-MFS在300 mV的过电位下的周转频率值为0.155 s，分别比目前最先进的IrO和RuO催化剂高80倍和190倍。此外，2Ni1Fe-MFS表现出100%的法拉第效率、大的电化学活性表面积和良好的长期耐久性，证实了其优异的OER性能。如此高的OER效率可归因于高表面积、密集的金属活性位点和界面传导路径的协同效应。这项工作为开发用于OER的简单、经济高效且高效的多孔Ni-Fe基催化剂提供了一种有前景的策略。
