Tuning In Situ Growth of CuO-TiO2/Ti Heterostructure Catalyst for Acceleration of Electrocatalytic Hydrogen Evolution Reaction

Due to the scarcity and high cost of precious metals, development of a noble metal-free, low-cost catalyst for hydrogen generation via water splitting is crucial. To develop an efficient HER catalyst, Ti, the ninth most abundant metal in Earth’s crust, was engineered systematically. The pristine transition metal titanium cannot drive an electrocatalytic hydrogen evolution reaction (HER) with an efficient rate in an acidic medium (0.5 M H2SO4). However, in situ growth of TiO2 film on Ti surface achieves HER activity, showing an overpotential for 10 mAcm−2 at 671.4 mV with a Tafel slope of 163.69 mV dec−1. The electrocatalytic performance was further boosted by immobilizing CuO particles onto the as-developed TiO2/Ti film, which shows 10 mA cm−2 overpotential at 543.7 mV with a Tafel slope of 101.09 mV dec−1. The CuO–TiO2/Ti heterostructured electrode exhibited remarkable long-term stability, with the current density increasing by 36% over 25 h of continuous operation, suggesting gradual electrochemical activation while maintaining robust catalytic performance. In this research, detailed structural, surface, and electrochemical investigations, including SEM–EDX, EIS, OCP, and XPS analyses, verified the optimized formation of the TiO2 layer and CuO incorporation, underscoring the positive impact of heterointerface engineering on HER enhancement.