Controllable surface reconstruction of copper foam for electrooxidation of benzyl alcohol integrated with pure hydrogen production

Abstract

Electrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals. Herein, we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam (CF) and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation (EBA), accompanied by the efficient hydrogen production. Correspondingly, the Cu(II)-dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range. The new species containing Cu2O, CuO, and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques. After 220-cycled activation (CF-220), the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2, while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE. The produced new species can endow the CF-220 with abundant acidity sites, which can enhance the adsorption toward Lewis-basicity benzyl alcohol, confirmed by NH3-temperature-programmed desorption. In situ Raman result further reveals that the as-produced CuO, Cu(OH)2, and Cu(OH)42− are the main active species toward the EBA process.