Regulating surface structures for efficient electron transfer across h-BN/TiO2/g-C3N4 photocatalyst for remarkably enhanced hydrogen evolution

This study reports significantly enhanced hydrogen production by conferring hierarchical porous TiO2 and g-C3N4 over hexagonal boron nitride (h-BN). This design enables enhanced light absorption capacity, suppressed electron-hole recombination, noble metal-free catalysts and robustness. The synthesis of h-BN/TiO2/g-C3N4 ternary composite by the deposition of g-C3N4 with morphological variation of Titanate entity (P25, 2D, and hierarchical porous TiO2 (HPT) over the h-BN nanoparticles in a simple hydrothermal approach. Systematic study confirms that the regulated h-BN/TiO2(HPT)/g-C3N4 ternary heterojunction nanocomposite exhibit remarkably enhanced rate of 2.02 mmolg(-1) h(-1) in comparison to 1.48 mmolg(-1) h(-1) and 0.98 mmolg(-1) h(-1) for h-BN/TiO2(P25)/g-C3N4 and h-BN/TiO2(2D)/g-C3N4 respectively. The hierarchical wormhole structured h-BN/TiO2(HPT)/g-C3N4 exhibits the highest charge separation efficiency and enhanced photocatalytic hydrogen generation. The lifetime of the as-synthesized photocatalysts follows the trend similar to the hydrogen production as 25 ns > 11 ns > 1.5 ns for h-BN/TiO2(HPT)/g-C3N4, h-BN/TiO2(P25)/g-C3N4, and h-BN/TiO2(2D)/g-C3N4, respectively. The electrochemical impedance spectra (EIS) reveals that the h-BN/TiO2(HPT)/g-C3N4 exhibited better interactions between the surface of TiO2 and h-BN/g-C3N4 and the corresponding flat-band potentials tends to be -0.82 eV, -0.55 eV, and -0.64 eV respectively, for titania modified ternary materials and possess adequate interfacial charge separation efficiency. The present observations unveiled that improved light-harvesting ability increased the photocatalytic activity surpassing the limitations of h-BN/TiO2 heterostructure for better photocatalysis.