Hydrothermally designed Ag-modified TiO2heterogeneous nanocatalysts for efficient hydrogen evolution by photo/electro/photoelectro-chemical water splitting.

Abstract

One compelling goal of carbon-neutrality is to advance sustainable energy applications through advanced functional nanomaterials for achieving remarkable performance in energy conversion processes, especially in green H2 energy. Here, Ag-modified TiO2 nanostructures with highly specific exposed surface sites have been fabricated hydrothermally, elucidating its prominence towards photocatalytic, and photo/-electrocatalytic H2 production. Further, the as-synthesized nanomaterials were investigated by XRD, electron microscopy (SEM/EDAX/TEM/HRTEM), ICP-MS, PL, Raman, UV-visible DRS, and BET surface area studies. The enhanced activity was established due to the exceptional optoelectronic properties and highly exposed active sites of the Ag-modified TiO2 nanocatalysts. The photocatalytic activity of 2.5% Ag-doped TiO2 photocatalyst demonstrated the highest hydrogen evolution, measuring 15.66 mmolg_cat^(-1)with 17.33% AQY. Moreover, for photo-electrolysis, 1% and 2.5% Ag-doped TiO2 nanocatalysts exhibited significantly improved activity with Tafel slopes of 162.49, 87.56 mV/dec and onset potentials of 0.77 V (at 1.55 mA/cm2), -0.96 V (at 10 mA/cm2) for OER and HER in alkaline and acidic conditions. Experiments indicated that incorporation of Ag ions in TiO2 boosted the H2 evolution due to the extraordinary surface properties and the presence of defect-sides /oxygen vacancies.