CuCoO2/CuO heterostructure: understanding the role of band alignment in selective catalysis for overall water splitting

Abstract

Employing a facile one-pot hydrothermal synthesis approach, in this work, we achieved the successful synthesis of a CuCoO₂/CuO heterostructure, which was characterized by an atomic-scale intimately bonded interface. This can be utilized as a reference for the synthesis of heterostructures involving multiple compounds and their secondary phases. Notably, the CuCoO₂/CuO heterostructure stands out for its superior performance in photocatalytic overall water splitting without relying on additional co-catalysts or sacrificial agents. In addition, this heterostructure displayed excellent electrocatalytic activity, photocatalytic activity for the degradation of trichloromethane, and promising PEC performance when utilized as a photocathode. A pivotal feature of the CuCoO₂/CuO heterostructure is its capacity to efficiently inhibit the migration of photogenerated holes from CuCoO₂ to CuO. This was attributed to the synergistic effects between the intrinsic interface electric field and pronounced valence band offset. Interestingly, this mechanism overcomes the traditional limitations associated with type-I heterostructures. Consequently, the two half-reactions of the overall water splitting process are selectively localized on opposite facets of the CuCoO₂/CuO heterostructure. Overall, our findings elucidate the profound implications of band alignment in these heterostructures, offering pivotal insights for the innovation and optimization of advanced heterostructure photo(electro)catalytic materials.