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.