Surface oxygen vacancy defects induced CoTiO3-x perovskite nanostructures for highly efficient catalytic activity from acidic and seawater electrolysis

Efficient electrocatalysts have great demand for improved hydrogen evolution (HE) from natural seawater splitting. In this work, a new type of oxygen (O2) vacancies and Ti3+ defective perovskite nanostructures (DPNSs) of D-CoTiO3-x were prepared by using eco-friendly sonochemical assisted laser irradiation technique (SCA-LIT) for the first time. These DPNSs were thoroughly characterized, and HE activity was evaluated to determine their electrocatalytic potential and efficiency improvement. The existence of abundantly available active sites in the prepared D-CoTiO3-x electrocatalyst composed of defective D-TiO2-x was confirmed through various physico-chemical measurements. The designed DPNSs-based working electrode exhibited excellent electrochemical performance due to its low over-potential (0.352 V), reduced Tafel slope (94.7 mV/dec), high double layer capacitance (235.3 mu F/cm2), large electrochemically active surface area (6.72 cm2) and exceptional long-term stability. The attained improvement in the HE efficiency was ascribed to the induced synergistic strong metal -support interaction (SMSI) effect of the surface O2 vacancies and Ti3+ defects in DPNSs that yielded high con-ductivity, high exposure of abundant active sites, wide active surface area, improved kinetics, and fast charge transport. Furthermore, Volmer-Heyrovsky (V-H) reaction mechanism was responsible for the generation of hydrogen (H2) by the proposed DPNSs-based electrode. In addition to the natural seawater, the D-CoTiO3-x DPNSs outperformed in terms of the electrocatalytic hydrogen activity and stability. Thus, our systematic approach for the fabrication of surface O2 vacancy and Ti3+ defect engineering DPNSs-based electrodes to produce H2 from natural seawater splitting may be beneficial for green energy generation, solving future environmental problems and energy demand crises.

Automated summary

In this work, a new type of oxygen vacancies and Ti3+ defective perovskite nanostructures (DPNSs) of D-CoTiO3-x were prepared using an eco-friendly sonochemical assisted laser irradiation technique. These DPNSs exhibited excellent electrochemical performance with low over-potential, reduced Tafel slope, high double layer capacitance, large electrochemically active surface area, and exceptional long-term stability. The improved hydrogen evolution efficiency was attributed to the induced synergistic strong metal-support interaction effect of the surface oxygen vacancies and Ti3+ defects in DPNSs, which enhanced conductivity, exposed abundant active sites, increased active surface area, improved kinetics, and facilitated fast charge transport. Furthermore, the DPNSs-based electrode operated through the Volmer-Heyrovsky reaction mechanism and outperformed in terms of electrocatalytic hydrogen activity and stability in natural seawater.