Threefold synergistic integration of platinum and graphene with titanium dioxide electrodes for photoelectrochemical hydrogen generation

The growing demand for sustainable energy has intensified interest in photoelectrochemical (PEC) water splitting for green hydrogen production. Titanium dioxide (TiO 2 ), though stable and cost-effective, suffers from a wide bandgap (∼3.2 eV) and rapid charge recombination. Here, a TiO 2 –carbon–Pt/graphene composite photoelectrode was developed to overcome these limitations and achieve efficient solar-driven hydrogen generation. Anatase TiO 2 nanoparticles and carbon nanoparticles (CNPs) were synthesized via sol–gel and pyrolytic methods, decorated with photodeposited platinum (Pt) nanoparticles, and integrated onto a graphene substrate. Structural and optical analyses confirmed successful component integration. CNPs enhanced visible-light absorption and induced photothermal effects, enhancing visible-light absorption through carbon-induced sub-bandgap states. Pt (2–5 nm) provided catalytic hydrogen evolution sites, while graphene enabled rapid charge transport. Under AM 1.5 G illumination (100 mW/cm 2 ) in 0.27 M KOH, the composite delivered an effective steady-state photocurrent density of ∼3.5 mA cm −2 at 0.5 V vs reversible hydrogen electrode during continuous PEC operation. The electrode achieved an applied bias photon-to-electron efficiency of 4.3%, with comparable performance under direct sunlight. It retained ∼82% of its initial photocurrent after 100 h continuous operation, confirming long-term durability. Scalable electrodes (10 cm²) exhibited near-linear scaling of steady-state photocurrent, confirming reproducibility while accounting for expected series-resistance effects at larger areas. Enhanced performance arose from synergistic effects: CNPs broadened absorption and accelerated kinetics, Pt catalyzed the hydrogen evolution reaction, and graphene facilitated efficient electron transport. Overall, this work highlights the effectiveness of synergistically integrating light-absorbing CNPs, catalytic platinum, and conductive graphene to overcome the intrinsic limitations of TiO 2 photoelectrodes.