Hydrothermally designed Ag-modified TiO₂ heterogeneous nanocatalysts for efficient hydrogen evolution by photo/electro/photoelectro-chemical water splitting

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 H₂energy. Here, Ag-modified TiO₂nanostructures with highly specific exposed surface sites have been fabricated hydrothermally, elucidating its prominence towards photocatalytic, and photo/-electrocatalytic H₂production. 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 TiO₂nanocatalysts. The photocatalytic activity of 2.5% Ag-doped TiO₂photocatalyst demonstrated the highest hydrogen evolution, measuring 15.66 mmolgcat-1with 17.33% apparent quantum yield. Moreover, for photo-electrolysis, 1% and 2.5% Ag-doped TiO₂nanocatalysts exhibited significantly improved activity with Tafel slopes of 162.49, 87.56 mV dec^-1and onset potentials of 0.77 V (at 1.55 mA cm^-2), -0.96 V (at 10 mA cm^-2) for oxygen evolution reaction and hydrogen evolution reaction in alkaline and acidic conditions. Experiments indicated that incorporation of Ag ions in TiO₂boosted the H₂evolution due to the extraordinary surface properties and the presence of defect-sides /oxygen vacancies.