Acid-enabled carbon cloth boosts activity and durability of Au/Co₃O₄ catalysts for acidic water electrolysis

Abstract The advancement of efficient and durable electrocatalysts is crucial for enhancing overall water-splitting technologies, particularly in harsh acidic environments. In this work, we treated carbon cloth (CC) with a mixture of HNO 3 and H 2 SO 4 to improve its surface properties and use it as a substrate for depositing Au/Co 3 O 4 catalysts. The acid-treated CC (TCC) exhibited enhanced hydrophilicity due to the introduction of increased hydroxyl and carboxyl functional groups, leading to a higher loading of the Au/Co 3 O 4 catalyst (3.36 wt% Co and 1.42 wt% Au) combined with uniform morphology compared to the untreated CC. The resulting Au/Co 3 O 4 /TCC catalyst demonstrated several desirable characteristics, including a higher specific surface area of 40.5 m 2 g −1 and smaller charge transfer resistance. When employed as a bifunctional electrocatalyst for overall water splitting, the Au/Co 3 O 4 /TCC exhibited a low cell voltage of 1.62 V in 0.5 M H 2 SO 4 electrolyte and outstanding durability, maintaining its performance over 24 h at a current density of 10 mA cm −2 without significant degradation, attributed to the strong interfacial interaction between the catalyst and the substrate. The enhanced wettability, surface area, and catalyst-support interaction arising from the acid treatment of the carbon cloth substrate were the key factors enabling the superior electrochemical performance of the Au/Co 3 O 4 /TCC catalyst system.