Innovative natural self-doped-CaTiO3 perovskite coupled with sulphonated biochar for hydrogen production under visible light

This study advances renewable energy technology by developing a low-cost, waste-derived photocatalyst system by using self-doped CaTiO₃ (SD-CaTiO₃) perovskite nanoparticles combined with watermelon sulfonated biochar (WMSB) for solar-driven green hydrogen production hydrogen production through visible-light-driven water splitting. The SD-CaTiO₃ was synthesized via two distinct approaches: a sol-gel method using nitrated Triesta Marble (NTM) as a calcium source and a molten-salt method combining Triesta Marble powder directly with TiO₂. Characterization revealed the sol-gel-derived material exhibited superior photocatalytic performance, featuring an orthorhombic crystalline structure with particle sizes ranging from 52.43 to 126.52 nm and a reduced bandgap of 2.39 eV compared to undoped CaTiO₃ (3.5 eV), enabling effective visible light absorption. Experimental optimization demonstrated significant hydrogen production differences between the two synthesis methods and the effect of WMSB incorporation. The sol-gel SD-CaTiO₃ alone achieved maximum H₂ production of 6781.48 μmol/L at pH 10 with 900 mg/L catalyst loading. The system enhanced performance when combined with 200 mg/L WMSB, reaching 9993.75 μmol/L at pH 2 under identical light conditions. The process was effectively modelled using an artificial neural network (ANN) with three hidden layers (Log-Sigmoid, Tan-Sigmoid, and linear activation functions) for the 1st, 2nd and 3rd hidden layers, respectively, achieving optimal predictive performance in just two training epochs. This study develops a waste-derived solar photocatalyst system for renewable hydrogen production (9993.75 μmol/L yield under visible light), directly advancing solar fuel technologies and circular economy integration for decarbonizing energy-intensive industries.