Band-matching transformation between CdS and BCNNTs with tunable p-n homojunction for enhanced photocatalytic pure water splitting

Effective photocatalytic evolution of H₂ from pure water splitting is a potential storage mode of renewable solar energy in which eliminating the constraint of sacrificial agents is essential to the improvement of solar-to-hydrogen (STH) conversion efficiency. Herein, based on the bandgap engineering theory, we propose a new band-matching transformation strategy to effectually regulate the spatial behavior of photocarriers, which is implemented in a novel CdS/BCNNTs photocatalytic system for the first time. Through the first-principle calculation, the nature of p-n homojunction in boron carbonitride nanotubes (BCNNTs) is studied and further manipulated via tuning the carbon content, thereby realizing the transformation of the band-matching relationship from type I to type Ⅱ. The variation in relative positions of band and the establishment of built-in field effectively guarantee the opposite migration direction of photogenerated charge carriers, thus greatly boosting their separation efficiency and survival time. The unique composite photocatalyst displays an ultrahigh photocatalytic hydrogen evolution of 526.02 μmol h⁻¹ g⁻¹ in pure water with a high apparent quantum yield of 4.01% at 420 nm. This study presents a promising insight into the precise regulation of band-matching engineering on designing advanced photocatalytic systems for efficient solar fuel conversion applications.