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Strong-Proton-Adsorption Co-based Electrocatalysts Achieve Active and Stable Neutral Seawater Splitting.

Ning WangPengfei OuSung-Fu HungJianan Erick HuangAdnan OzdenJehad AbedIvan GrigioniClark ChenRui Kai MiaoYu YanJinqiang ZhangZiyun WangRoham DorakhanAhmed BadreldinAhmed Abdel-WahabDavid SintonYongchang LiuHongyan LiangEdward H Sargent
Published in: Advanced materials (Deerfield Beach, Fla.) (2023)
Direct electrolysis of pH-neutral seawater to generate hydrogen is an attractive approach for storing renewable energy. However, due to the anodic competition between the chlorine evolution and the oxygen evolution reaction (OER), direct seawater splitting suffers from a low current density and limited operating stability. Exploration of catalysts enabling an OER overpotential below the hypochlorite formation overpotential (∼ 490 mV) is critical to suppress the chloride evolution and facilitate the seawater splitting. Here we report a proton-adsorption-promoting strategy to increase the OER rate, resulting in a promoted and more stable neutral seawater splitting. The best catalysts herein are strong-proton-adsorption (SPA) materials such as palladium-doped cobalt oxide (Co 3- x Pd x O 4 ) catalysts. These achieve an OER overpotential of 370 mV at 10 mA/cm 2 in pH-neutral simulated seawater, outperforming Co 3 O 4 by a margin of 70 mV. Co 3- x Pd x O 4 catalysts provide stable catalytic performance for 450 hours at 200 mA/cm 2 and 20 hours at 1 A/cm 2 in neutral seawater. Experimental studies and theoretical calculations suggest that the incorporation of SPA cations accelerates the rate-determining water dissociation step in neutral OER pathway, and control studies rule out the provision of additional OER sites as a main factor herein. This article is protected by copyright. All rights reserved.
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