Designed a hollow Ni2P/TiO2 S-scheme heterojunction for remarkably enhanced photoelectric effect for solar energy harvesting and conversion

Abstract

Harvesting and converting solar energy is a promising strategy for addressing energy and environmental crises. To achieve this strategy, numerous semiconductors and heterojunctions have been explored and developed. However, the low utilization rates of light and low charge separation efficiency are still major drawbacks limiting its development. The structure and electron transfer paths of semiconductor heterojunctions are important for solar energy harvesting and conversion. A one-dimensional hollow structure has excellent light scattering and reflection effects that can improve the harvesting and conversion of solar energy. Furthermore, S-scheme has recently become a hot topic of research because of its ability to weed out useless photoelectrons and holes while retaining powerful ones. In this study, a hollow Ni₂P/TiO₂ S-scheme heterojunction was designed to harvest solar energy and enhance the photoelectric effect. The Ni₂P/TiO₂ heterojunction has excellent photoelectric separation effects, which are confirmed by photoelectrochemical characterization results and density functional theory (DFT) calculations. Consequently, the hollow Ni₂P/TiO₂ heterojunction provides good photocathodic protection under visible light irradiation, and the surface potential of 304ss coupled with the Ni₂P/TiO₂ heterojunction decreases to −0.83 V in a 3.5% NaCl solution. Laser scanning confocal microscopy (LSCM) shows that the 3D morphology and roughness of the 304ss surface changes slightly with the photocathodic protection of the Ni₂P/TiO₂ composite. Based on the band matching and electron spin resonance (ESR) experimental results, the S-scheme interfacial charge transfer path was confirmed. This study demonstrates the potential of the Ni₂P/TiO₂ S-scheme heterojunction for photocathodic protection and can inspire future exploration of the S-scheme heterojunction for photocathodic protection.