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.