Promoting Alcohols Electrooxidation Coupled with Hydrogen Production via Asymmetric Pulse Potential Strategy

Abstract

Electrocatalytic organic oxidation coupled with hydrogen (H₂) production emerges as a profitable solution to simultaneously reduce overall energy consumption of H₂ production and synthetic high-value chemicals. Noble metal catalysts are highly efficient electrocatalysts in oxidation reactions, but they deactivate easily weakening the benefit in actual production. Herein, we report a universal asymmetric pulse potential strategy to achieve long-term stable operation of noble metals for various alcohol oxidation reactions and noble metal catalysts. For example, by pulsed potentials between 0.8 V and 0 V vs. RHE, palladium (Pd)-catalyzed glycerol (GLY) electrooxidation can continuously proceed for more than 2800 h with glyceric acid (GLA) selectivity of >70 %. Whereas, Pd electrocatalyst becomes nearly deactivated within 6 h of reaction under conventional potentiostatic strategy. Experimental and theoretical calculation results reveal that the generated electrophilic OH* from H₂O/OH^- oxidation on Pd (denoted as Pd-OH*) acts as main active species for GLY oxidation. However, Pd-OH* is prone to be oxidized to PdO_x resulting in performance decay. When a short reduction potential (e.g., 0 V vs. RHE for 5 s) is powered, PdO_x can be reversibly reduced to restore the current. Moreover, we tested the feasibility of this strategy in a flow electrolyzer, verifying the practical application potential.