Highly Durable Nanoporous Cu_2–xS Films for Efficient Hydrogen Evolution Electrocatalysis under Mild pH Conditions

Abstract

Copper-based hydrogen evolution electrocatalysts are promising materials to scale-up hydrogen production due to their reported high current densities; however, electrode durability remains a challenge. Here, we report a facile, cost-effective, and scalable synthetic route to produce Cu2–x S electrocatalysts, exhibiting hydrogen evolution rates that increase for ∼1 month of operation. Our Cu2–x S electrodes reach a state-of-the-art performance of ∼400 mA cm–2 at −1 V vs RHE under mild conditions (pH 8.6), with almost 100% Faradaic efficiency for hydrogen evolution. The rise in current density was found to scale with the electrode electrochemically active surface area. The increased performance of our Cu2–x S electrodes correlates with a decrease in the Tafel slope, while analyses by X-ray photoemission spectroscopy, operando X-ray diffraction, and in situ spectroelectrochemistry cooperatively revealed the Cu-centered nature of the catalytically active species. These results allowed us to increase fundamental understanding of heterogeneous electrocatalyst transformation and consequent structure–activity relationship. This facile synthesis of highly durable and efficient Cu2–x S electrocatalysts enables the development of competitive electrodes for hydrogen evolution under mild pH conditions.

Sulfur Changes the Electrochemical CO2 Reduction Pathway over Cu Electrocatalysts

“…As shown in Figure 2d, the partial current density of formate maintains almost constant during 12 h of continuous electrolysis, indicating excellent catalytic stability of 1.5 %S-Cu 2 O. The increase in total current density is also consistent with a previous report related to Cu 2 À x S, [21] which may be due to continuous structural evolution during electroreduction.…”