Designing catalytic materials with enhanced stability and activity is crucial for sustainable electrochemical energy technologies. RuO2 is the most active material for oxygen evolution reaction (OER) in electrolysers aiming at producing ‘green’ hydrogen, however it encounters critical electrochemical oxidation and dissolution issues during reaction. It remains a grand challenge to achieve stable and active RuO2 electrocatalyst as the current strategies usually enhance one of the two properties at the expense of the other. Here, we report breaking the stability and activity limits of RuO2 in neutral and alkaline environments by constructing a RuO2/CoOx interface. We demonstrate that RuO2 can be greatly stabilized on the CoOx substrate to exceed the Pourbaix stability limit of bulk RuO2. This is realized by the preferential oxidation of CoOx during OER and the electron gain of RuO2 through the interface. Besides, a highly active Ru/Co dual-atom site can be generated around the RuO2/CoOx interface to synergistically adsorb the oxygen intermediates, leading to a favourable reaction path. The as-designed RuO2/CoOx catalyst provides an avenue to achieve stable and active materials for sustainable electrochemical energy technologies.
Electrochemical energy devices, such as fuel cells and metal–air batteries, convert chemical energy directly into electricity without adverse environmental impact. Attractive alternatives to expensive noble metals used in these renewable energy technologies are earth‐abundant transition metal oxides. However, they are often limited by catalytic and conductive capabilities. Here reported is a spinel oxide, Co2VO4, by marrying metallic vanadium atomic chains with electroactive cobalt cations for superior oxygen reduction reaction (ORR)—a key process for fuel cells, metal–air batteries, etc. The experimental and simulated electron energy‐loss spectroscopy analyses reveal that Co2+ cations at the octahedral sites take the low spin state with one eg electron (t2g6eg1), favoring advantageous ORR energetics. Measurement of actual electrical conductivity confirms that Co2VO4 has several orders of magnitude increase when compared with benchmark cobalt oxides. As a result, a zinc–air battery with new spinel cobalt vanadate oxide as the ORR catalyst shows excellent performance, together with a record‐high discharge peak power density of 380 mW cm−2. Crucially, this is superior to state‐of‐the‐art Pt/C‐based device and is greatest among zinc–air batteries assembled with metal, metal oxide, and carbon catalysts. The findings present a new design strategy for highly active and conductive oxide materials for a wide range of electrocatalytic applications, including ORR, oxygen evolution, and hydrogen evolution reactions.
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