Dual-doped ZnO nanocomposites for superior photocatalytic hydrogen generation

Abstract

The development of efficient and stable photocatalysts for hydrogen (H2) generation is crucial for sustainable energy applications. This study addresses the limitations of pristine zinc oxide (ZnO), its wide bandgap (~ 3.37 eV), and rapid charge recombination by synthesizing aluminum (Al) and cerium (Ce) co-doped ZnO nanocomposites (ACZO) via a scalable hydrothermal method. Structural and optical characterizations confirmed successful dopant incorporation, reduced crystallite size, and enhanced light absorption, with a narrowed bandgap of 2.64 eV. Further, these modifications suppress electron–hole recombination, as evidenced by a 70% reduction in photoluminescence intensity for ACZO compared to ZnO. Under simulated solar irradiation, the optimized ACZO nanocomposite achieved an H2 generation rate of 1474 μmol/g.h, a 2.8-fold increase over pristine ZnO, outperforming single-doped counterparts (AZO: 1.25-fold; and CZO: 1.84-fold). The optimal catalyst dosage was determined to be 1.5 g/L, balancing dispersion and light absorption. Furthermore, ACZO exhibited excellent photostability over multiple cycles, demonstrating its potential for long-term applications. This study highlights the effectiveness of dual doping in enhancing ZnO’s photocatalytic efficiency, positioning ACZO as a promising candidate for scalable solar-driven hydrogen production.