TiB2 derived nanosheets co-immobilized with triangular gold nanoparticles elicit fast and stable photocatalytic hydrogen evolution

Abstract

Transition metal diborides are recently being revisited from the viewpoint of yielding 2D nanostructures owing to their layered topology and the inherent presence of boron honeycomb planes. In this report, we show that nanosheets derived from titanium diboride (TiB2), when co-immobilized with anisotropic gold nanoparticles, demonstrate an impressive photocatalytic behavior towards hydrogen evolution. We found that this novel nano construct could achieve H2 evolution rates of up to 1.13 mmol g-1h-1 at neutral pH and simulated light irradiation. This production rate is significant considering the fact that we neither employed any co-catalyst or electron/hole scavenging chemical species nor applied any external bias. In addition, the catalyst could continuously produce H2 for at least 30 h. We also found that the construct was active under direct sunlight exposure. The co-immobilized construct also showed photocatalytic activity under UV and NIR irradiations. This is the first report wherein TiB2 derived nanosheets have been employed towards catalyzing the HER. We attribute the mechanism of photocatalytic H2 evolution to either better electron/hole pair separation or direct electron transfer from the photosensitive gold nanoparticles to the nanosheets (through the formation of a Schottky barrier). This report showcases the rich potential of functionalized metal diboride nanosheets and their constructs for next-generation photocatalysts.