Design of SnO 2 :Ni,Ir Nanoparticulate Photoelectrodes for Efficient Photoelectrochemical Water Splitting.

Currently, hydrogen generation via photocatalytic water splitting using semiconductors is regarded as a simple environmental solution to energy challenges. This paper discusses the effects of the doping of noble metals, Ir (3.0 at.%) and Ni (1.5-4.5 at.%), on the structure, morphology, optical properties, and photoelectrochemical performance of sol-gel-produced SnO 2 thin films. The incorporation of Ir and Ni influences the position of the peaks and the lattice characteristics of the tetragonal polycrystalline SnO 2 films. The films have a homogeneous, compact, and crack-free nanoparticulate morphology. As the doping level is increased, the grain size shrinks, and the films have a high proclivity for forming Sn-OH bonds. The optical bandgap of the un-doped film is 3.5 eV, which fluctuates depending on the doping elements and their ratios to 2.7 eV for the 3.0% Ni-doped SnO 2 :Ir Photoelectrochemical (PEC) electrode. This electrode produces the highest photocurrent density ( J ph = 46.38 mA/cm 2 ) and PEC hydrogen production rate (52.22 mmol h -1 cm -2 at -1V), with an Incident-Photon-to-Current Efficiency (IPCE% )of 17.43% at 307 nm. The applied bias photon-to-current efficiency (ABPE) of this electrode is 1.038% at -0.839 V, with an offset of 0.391% at 0 V and 307 nm. These are the highest reported values for SnO 2 -based PEC catalysts. The electrolyte type influences the J ph values of photoelectrodes in the order J ph (HCl) > J ph (NaOH) > J ph (Na 2 SO 4 ). After 12 runs of reusability at -1 V, the optimized photoelectrode shows high stability and retains about 94.95% of its initial PEC performance, with a corrosion rate of 5.46 nm/year. This research provides a novel doping technique for the development of a highly active SnO 2 -based photoelectrocatalyst for solar light-driven hydrogen fuel generation.