Efficient overall water splitting in acid with anisotropic metal nanosheets
Dongshuang Wu, Kohei Kusada, Satoru Yoshioka, Tomokazu Yamamoto, Takaaki Toriyama, Syo Matsumura, Yanna Chen, Okkyun Seo, Jaemyung Kim, Chulho Song, Satoshi Hiroi, Osami Sakata, Toshiaki Ina, Shogo Kawaguchi, Yoshiki Kubota, Hirokazu Kobayashi, Hiroshi Kitagawa
Abstract
Abstract Water is the only available fossil-free source of hydrogen. Splitting water electrochemically is among the most used techniques, however, it accounts for only 4% of global hydrogen production. One of the reasons is the high cost and low performance of catalysts promoting the oxygen evolution reaction (OER). Here, we report a highly efficient catalyst in acid, that is, solid-solution Ru‒Ir nanosized-coral (RuIr-NC) consisting of 3 nm-thick sheets with only 6 at.% Ir. Among OER catalysts, RuIr-NC shows the highest intrinsic activity and stability. A home-made overall water splitting cell using RuIr-NC as both electrodes can reach 10 mA cm −2 geo at 1.485 V for 120 h without noticeable degradation, which outperforms known cells. Operando spectroscopy and atomic-resolution electron microscopy indicate that the high-performance results from the ability of the preferentially exposed {0001} facets to resist the formation of dissolvable metal oxides and to transform ephemeral Ru into a long-lived catalyst.