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 seawater splitting. Here, a proton‐adsorption‐promoting strategy to increase the OER rate is reported, 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 (Co3–xPdxO4) catalysts. These achieve an OER overpotential of 370 mV at 10 mA cm−2 in pH‐neutral simulated seawater, outperforming Co3O4 by a margin of 70 mV. Co3–xPdxO4 catalysts provide stable catalytic performance for 450 h at 200 mA cm−2 and 20 h 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.
The electrocatalytic synthesis of acetic acid from CO2 offers a low carbon alternative for the production of an important chemical feedstock and precursor to polymers, solvents, food additives and textiles. CO electroreduction bypasses the CO2 crossover energy penalty suffered by direct CO2 electroreduction, motivating interest in a cascade approach of CO2-to-CO followed by COto-acetic acid. However, for the process to achieve feasibility, major advancements in CO-toacetate faradaic efficiency, partial current density, and product concentration are needed. Here we report a catalyst design strategy in which off-target intermediates are destabilized, an approach that leads to 70% faradaic efficiency (FE) to acetate at 200 mA cm -2 using an Ag-Cu2O catalyst.We demonstrate 18 hours of stable operation in a membrane electrode assembly, with the system producing 5 wt.% acetate at 100 mA cm -2 and a full cell energy efficiency of 25%, a 2-fold improvement upon the highest-energy-efficiency electrosynthesis in prior reports.
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