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 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 mmol g cat − 1 with 17.33% apparent quantum yield. 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⁻¹ and 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 TiO₂ boosted the H₂ evolution due to the extraordinary surface properties and the presence of defect-sides /oxygen vacancies.