Escalating\nthe Catalytic Water Splitting on Si–gC<sub>3</sub>N<sub>4</sub>/Al–rTiO<sub>2</sub> System: Synergy between\nSPR and Charge Transfer

Hybrid photocatalytic systems have drawn significant\nattention\nto produce renewable hydrogen from water splitting. High performances\nof hybrid catalysts depend upon synergism and effective charge transfer,\nspecifically during the photoreaction. In this work, Cu–Fe-loaded\ndual-doped hybrid Si–gC<sub>3</sub>N<sub>4</sub>/Al–rTiO<sub>2</sub> catalysts have been synthesized and introduced. Cu–Fe\ncocatalysts were deposited by coprecipitation and chemical reduction,\nwhereas Si and Al doping was in situ achieved on hydrothermal reactions.\nCatalysts were abbreviated as Cu–Fe@Si–CN/Al–TO,\nwhere CN = gC<sub>3</sub>N<sub>4</sub> and TO = rTiO<sub>2</sub>.\nMorphology and optical characteristics have been evaluated by X-ray\ndiffraction (XRD), Raman, Fourier transform infrared spectroscopy\n(FTIR), scanning electron microscopy (SEM), atomic force microscopy\n(AFM), UV–vis/drs, photoluminescence (PL), electron dispersive\nX-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS),\nwhereas the electrochemical response has been justified via electron\nimpedance spectroscopy (EIS) technique. All photoreactions have been\nperformed in a quartz reactor (150 mL/Velp-UK), whereas hydrogen evolution\nactivities have been monitored on a gas chromatograph (GC–TCD/Shimadzu-Japan).\nResults depict that existence of Al dopants reduced the band gap of\nrTiO<sub>2</sub> and has extended its photon/light absorption capability.\nThe Si dopants in gC<sub>3</sub>N<sub>4</sub> sheets enhance the overall\nelectron transfer by contributing relatively higher charge induction\nto active sites. It has been predicted that Cu generates high-energy\nelectrons (i.e., surface plasmon resonance, SPR-induced charges) that\nprogressively transfer to Si–gC<sub>3</sub>N<sub>4</sub>, where\nthey are dragged to Al–rTiO<sub>2</sub> via Fe cocatalysts\nthat act as an electron mediator. Although there are many challenges\nahead, the aforementioned catalyst has potential to replace the costly\nand conventional catalysts that have been priorly used for hydrogen\ngeneration technologies.