A direct Z-scheme-based 2D graphdiyne/cupric oxide heterojunction for enhancing solar-to-hydrogen conversion efficiency

Abstract

We present a novel approach to enhance the hydrogen evolution reaction by directly introducing the Z-scheme by encapsulating 2D graphdiyne into CuO foam for the first time via the Glaser coupling reaction, which relies on the presence of Cu⁺ ions to form 2D graphdiyne. Since CuO doesn't have intrinsic Cu⁺ ions and thus cannot directly participate in the Glaser coupling reaction, an annealing process is applied to form Cu⁺ ions on the CuO surface to solve this problem. As a result, this strategy successfully forms both encapsulation and a direct Z-scheme configuration, significantly improving the HER and long-term stability. Compared to CuO modified with platinum single atoms, the HER performance is enhanced by 30%. Under 1 sun illumination, a HER and Faraday efficiency of 70 μmol h⁻¹ cm⁻² and 88.6% are achieved. This study presents an effective surface engineering strategy, highlighting its strong potential as an efficient photoelectrode for sustainable hydrogen generation.