Dual modification of cobalt silicate nanobelts by Co₃O₄ nanoparticles and phosphorization boosting oxygen evolution...

Oxygen evolution reaction (OER) process is the "bottleneck" of water splitting, and the low-cost and high-efficient OER catalysts are of great importance and attractive but they are still challenging. Herein, a dual modification strategy is developed to tune and enrich the structure of cobalt silicate (Co₂SiO₄) showing boosted OER properties. Cobalt oxide (Co₃O₄) decorated Co₂SiO₄ nanobelts, denoted as CS, is firstly prepared using a Co-based precursor by a facile hydrothermal reaction. Then, cobalt phosphide (CoP) nanoparticles are in-situ grown on CS (denoted as CS-P) by the phosphorization process, which provide many active sites and boost the surface reactivity. The experimental results and density function theory (DFT) calculations both reveal that the CoP on CS can improve the conductivity and ensure fast kinetics, thus leading to boost the OER properties of Co₂SiO₄. When the phosphorization temperature is at 400 °C (CS-P400), it gains the lowest overpotential of 297 mV, which is much lower than CS (340 mV) and Co₂SiO₄ (409 mV) at 10 mA·cm^-2, and even superior to the state-of-the-art transition metal silicates. CS-P400 also achieves high electrochemical active surface area (ECSA) and small Tafel slope owing to its porous structures with large specific surface area and nanosheet-like structures which are good for exposing many active sites and favorable to the fast kinetics. This work not only provides a dual modification route to boost catalytic activity of Co₂SiO₄ (CS-P400), but also sheds light on a new avenue for developing highly dispersed CoP on silicates to boost OER performances.