Highly Active Electrochemical Hydrogen Production from Water Using CaTiO₃ Loaded with Cu_2−xO

This study presents the synthesis of calcium titanate (CaTiO₃, CTO) perovskite particles via a straightforward flux method, followed by modification with a Cu_2−xO cocatalyst to form thin films on both fluorine-doped tin oxide (FTO) and carbon paper substrates. The electrochemical performance of these Cu_2−xO/CTO films were rigorously evaluated in the hydrogen evolution reaction (HER). Notably, the CTO modified with 4.0 wt% Cu_2−xO on carbon paper exhibited a remarkable increase in HER activity, achieving a current density of 37 mA cm⁻²—significantly higher than that of pristine CTO. The superior performance of the carbon paper-supported films can be attributed to the substrate’s unique fibrous porous structure and exceptional conductivity, which collectively enhance electrocatalytic efficiency. This exceptional performance is linked to the high dispersion of Cu_2−xO on the CTO surface and the synergistic interactions within the perovskite framework. These findings underscore the potential of Cu_2−xO cocatalysts as effective non-noble materials for electrocatalytic water splitting, paving the way for future innovations in sustainable energy technologies.