A robust N@g-C3N4NiMoIr aerogel photoanode for efficient photoelectrochemical water splitting: Synergistic effects and interfacial kinetics

Photoelectrochemical (PEC) water splitting is a promising strategy for sustainable hydrogen generation, but it is often limited by sluggish charge transfer and reaction kinetics. In this study, a trimetallic aerogel photoanode composed of nitrogen-doped graphitic carbon nitride integrated with Ni, Mo, and Ir nanoparticles (N@g-C 3 N 4 -NiMoIr) was synthesized through a simple NaBH 4 reduction–gelation process. The resulting porous architecture and strong synergistic interactions among the three metals significantly enhanced light absorption, charge separation, and catalytic activity. Optical and electrochemical analyses confirmed improved visible-light harvesting, suppressed electron–hole recombination, and efficient interfacial charge transport. The optimized N@g-C 3 N 4 -NiMoIr photoanode generated a maximum photocurrent density of 7.89 mA cm −2 at 1.23 V vs. RHE and an ABPE of 0.22 %, while retaining 86 % of its photocurrent after 11,000 s of operation. These results highlight the potential of synergistic multi-metal aerogel systems for advancing efficient and stable PEC water-splitting technologies. • N@g-C 3 N 4 –NiMoIr aerogel synthesized using a simple NaBH 4 -assisted gelation route. • NiMoIr loading improves light absorption, charge separation, and PEC stability. • High photocurrent of 7.89 mA/cm 2 and 0.22 % ABPE achieved under AM 1.5G illumination. • The photoanode retains 86 % photocurrent after 11,000 s, confirming strong durability.