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

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.

Automated summary

In this study, a CuCoO2/CuO heterostructure was successfully synthesized using a simple one-pot hydrothermal synthesis approach. The heterostructure exhibited superior performance in both photocatalytic overall water splitting and electrocatalytic reactions. The unique band alignment mechanism of the CuCoO2/CuO heterostructure efficiently inhibited the migration of photogenerated holes, which overcame the limitations associated with traditional type-I heterostructures. These findings provide important insights for the innovation and optimization of advanced heterostructure photo(electro)catalytic materials.