2D boron-infused photocatalysts: driving green hydrogen via photocatalytic water splitting

The transition to renewable and sustainable energy sources has positioned hydrogen as a key component of future energy systems due to its high energy density and zero-carbon emissions. Photocatalytic water splitting has emerged as a particularly promising solar-to-fuel conversion pathway, yet conventional semiconductors are constrained by wide band gaps, fast charge recombination and poor stability. Two-dimensional (2D) boron-based nanostructures, therefore, attracted attention as next-generation photocatalysts owing to their tunable electronic properties, high carrier mobility and structural versatility. This review highlights recent progress in boron-containing photocatalysts, focusing on hexagonal boron nitride (h-BN), boron carbon nitride (BCN), boron-doped graphitic carbon nitride (boron-doped g-C3N4) and borophene. h-BN, despite its wide band gap, shows enhanced activity when integrated into heterostructures (e.g. CdS@h-BN/rGO) or doped with carbon, oxygen or fluorine. BCN, with its tunable band gap and antioxidative stability, demonstrates high hydrogen evolution efficiency in Cu2O composites or oxygen-deficient BCN-TiO2 hybrids. B-g-C3N4 benefits from boron incorporation into the heptazine framework, improving charge separation and light absorption. Borophene, with high conductivity and abundant active sites, offers strong reactivity, though stability remains a challenge. Collectively, these materials demonstrate distinctive enhancement strategies and highlight their transformative potential for solar-driven water splitting and sustainable hydrogen production.