Effective graphene incorporation of strontium niobate-doped titanium oxide for photocatalytic hydrogen production

To meet the increasing global demand for clean energy and mitigate the impact of CO2 emissions on climate change, the production of photocatalytic hydrogen through water splitting is a compelling scientific and technological objective. Despite considerable efforts, the establishment of a reliable and highly efficient system for hydrogen generation powered by visible light remains challenging. In this study, we developed a solar-active strontium niobate-doped titanium oxide incorporated with graphene (Sr2Nb2O7-rGO-TiO2), characterized by various analytical techniques such as optical, morphological, HR-TEM, XPS, and XRD. Sr2Nb2O7-rGO-TiO2 demonstrated enhanced photocatalytic H2 evolution under solar irradiation without requiring precious-metal doping. The maximum H2 production performance rate of 1769 mu mol/g/h was attained with the Sr2Nb2O7-r-GO-TiO2 composites, significantly surpassing those of the bare (TiO2: 210 mu mol/g/h, Sr2Nb2O7: 88 mu mol/g/h) and binary (TiO2-rGO: 430 mu mol/g/h, Sr2Nb2O7-rGO: 176 mu mol/g/h, and Sr2Nb2O7-TiO2: 880 mu mol/g/h) photocatalysts. The enhanced performance of the Sr2Nb2O7-rGO-TiO2 composite is attributable to the synergistic effect of rGO acting as an electron-transfer bridge. Thus, with the integration of rGO, absorption is attainable in an extended range up to 445 nm (2.90 eV), suggesting that the composite material could enable the catalyst to absorb more visible light. Additionally, the composite exhibited minor degradation after five consecutive cycles, demonstrating its excellent stability and reusability for hydrogen generation. Based on a comprehensive evaluation of the ESR and transient photocurrent response, a potential Z-scheme mechanism for the photocatalytic H2 generation activity over Sr2Nb2O7-rGO-TiO2 was suggested. The Z-scheme processability allows more electrons to contribute to the H2 evolution reduction. In this study, we developed a non-toxic, costeffective, highly efficient, and recyclable photocatalyst for H2 production.