Electron-rich interface of Cu-Co heterostructure nanoparticle as a cocatalyst for enhancing photocatalytic hydrogen evolution

Heterogeneous nano-metal structures are widely used in the field of photocatalysis as an efficient cocatalyst, but the structure-activity relationship has not been elucidated clearly. In this work, a classical CuCo@C nanoparticle with a core of bimetallic CuCo and a carbon shell was used as a cocatalyst to explore and reveal the mechanism of interfacial effect for enhanced photocatalytic hydrogen evolution. It was found that the bimetallic CuCo had a heterogeneous structure with abundant Cu-Co interfaces. The desirable visible-light-driven photocatalytic hydrogen evolution rate of CuCo@C/g-C3N4 was much higher than that of Cu@C/g-C3N4, Co@C/g-C3N4, and superior to that of the control group loaded with 1 wt% Pt (Pt/g-C3N4). According to the experimental characterizations and density functional theory calculations, electrons were enriched at the Cu-Co interface, which can promote the electron-hole pairs separation and accelerate charge transfer of the g-C3N4 host photocatalysts. On the other hand, the surface carbon layer and Cu-Co interface modulated the H adsorption free energy on the CuCo@C, which was favorable for hydrogen evolution. It is conceivable that further investigating and tuning different metal interfaces will facilitate the large-scale application of bimetallic cocatalysts.

Automated summary

This study investigated the mechanism of interfacial effect on enhanced photocatalytic hydrogen evolution using CuCo@C nanoparticles as cocatalysts. The CuCo@C/g-C3N4 showed a higher rate of visible light-driven photocatalytic hydrogen evolution compared to other control groups. Experimental and theoretical calculations revealed that the enrichment of electrons at the Cu-Co interface promoted the separation of electron-hole pairs and accelerated charge transfer. Additionally, the carbon layer and Cu-Co interface regulated the adsorption free energy of hydrogen on CuCo@C, favoring hydrogen evolution.