Role of plasmonic nanoparticles for oxygen and hydrogen evolution reactions in photoelectrochemical water splitting

Monoclinic scheelite phase of n-type bismuth vanadate (BiVO₄) as a solar-driven catalyst-based photoanode is emerging as an optimistic approach for efficient photoelectrochemical water splitting because of features such as maximum light harvesting potential in visible spectrum, nontoxicity, earth abundance and stability under electrochemical conditions. The photoelectrochemical cell is a coherent and eco-friendly technique to convert solar energy into a renewable energy source like hydrogen with zero carbon emissions. Here we fabricated nanocomposite-based photoanodes RGO/CNT/BiVO₄, RGO/CNT/Ni/BiVO₄, RGO/CNT/Cu/BiVO₄ and RGO/CNT/Ni/Cu/BiVO₄ by layering reduced graphene oxide (RGO) and carbon nanotubes (CNTs) to act as a transmission channel for fast transport of electrons with non-noble electrocatalyst nickel (Ni) and copper (Cu) nanoparticles and visible driven photoactive bismuth vanadate (BiVO₄) nanomaterial on fluorine-doped tin oxide by using electrodeposition and the drop casting method. The absorption edge was analyzed using ultraviolet–visible spectroscopy and Tauc plots, which clearly indicated a decreasing trend in the bandgap of BiVO₄, thereby increasing the absorption spectrum with improved charge transfer rate. To scrutinize the proficiency of the electrochemical reaction during water splitting for hydrogen evolution reaction and oxygen evolution reaction of photoanodes, electrochemical testing was done using linear sweep voltammetry, which distinctly showed that the fabricated photoanode RGO/CNT/Ni/Cu/BiVO₄ possessed high photo-response at an overpotential of 190 mV, with a lower Tafel slope of 119 mV dec⁻¹.