Nanostructured electroless Ni deposited SnO₂ for solar hydrogen production

Herein, Ni-decorated SnO₂ (Ni@SnO₂) nanostructures have been synthesized using SnO₂ as a matrix via a simple electroless deposition method for the generation of hydrogen, a potent near-future fuel. XRD analysis confirmed the generation of rutile SnO₂ in Ni@SnO₂. FESEM and FETEM imaging exhibited the formation of SnO₂ nanoparticles with a size of 10-50 nm, which are deposited with Ni nanoparticles (5-7 nm) and intermittent films (thickness 1-2 nm). The associated EDS elemental mapping validated Ni deposition on the surface of the SnO₂ nanoparticles, further supplemented by FTIR, Raman and XPS analysis. Slight red shifts in the band gaps of the Ni@SnO₂ nanostructures (in the range of 3.53-3.65 eV) compared to the pristine SnO₂ nanoparticles (3.72 eV) were observed. Also, intensity quenching of the band gap and associated defect peaks were observed in PL analysis. The Ni@SnO₂ nanostructures were used as photocatalysts and exhibited proficient hydrogen evolution. Among the samples, the 0.3 wt% Ni@SnO₂ nanostructures showed the greatest hydrogen evolution, i.e., ∼50 μmol g^-1 h^-1 under visible light irradiation versus pristine SnO₂ (8.5 μmol g^-1 h^-1) owing to the enhanced density of active sites and effective charge separation. It is noteworthy that the hydrogen evolution is much better as compared to earlier reports of Pt-doped-SnO₂ based materials.