Enhanced hydrogen evolution kinetics via GaN/g-C3N4 heterojunction engineering

Among various semiconductors evaluated for photoelectrochemical (PEC) water splitting, gallium nitride (GaN) has emerged as a promising photoelectrode material due to its wide, direct bandgap, which allows for more efficient sunlight utilization. To address the issue of severe surface states that hinder its performance, graphitic carbon nitride (g-C₃N₄) was introduced as a passivation layer. The resulting GaN/g-C₃N₄ heterojunction demonstrates a significant enhancement in PEC performance compared to pristine GaN nanorods (NRs), including a notable increase in photocurrent density. Importantly, this heterostructure is also capable of driving PEC water splitting under zero external bias, which is primarily attributed to the efficient charge separation and transfer enabled by the Z-scheme mechanism. Overall, this study offers a novel strategy for passivating surface states in nanomaterials and underscores the promising role of g-C₃N₄ in PEC water splitting applications.