Cobalt oxide decorated three-dimensional amorphous carbon/cobalt silicate composite derived from bamboo leaves enables the enhanced oxygen evolution reaction

• Co-rich C/CoSi is developed and proved as a potential OER catalyst. • Co decoration can significantly improve the OER performance of 3D C/CoSi. • The overpotential of Co-rich C/CoSi at 10 mA·cm −2 is 349 mV, which is much lower than C/CoSi. • Co-rich C/CoSi shows large electroactive surface area and long stability. Cobalt oxide decorated amorphous carbon/cobalt silicate (denoted as Co-rich C/CoSi) is developed and proved as a potential OER catalyst. The three-dimensional (3D) Co-rich C/CoSi composite is synthesized using the renewable bamboo leaves as raw materials and silicon suppliers undergoing the calcination, hydrothermal and adsorption processes. The decoration of Co can greatly improve the OER performance of carbon/cobalt silicate (C/CoSi). The overpotential of Co-rich C/CoSi is 349 mV at 10 mA·cm −2 and Tafel slope is 77 mV·dec -1 , which are lower than those of C/CoSi (448 mV and 84 mV·dec -1 ). The values are even superior to many reported transition metal-based electrocatalysts. Furthermore, the Co-rich C/CoSi shows large electroactive surface area and long stability (98.7% OER capacity retention after 15 h). This work not only develops a strategy to synthesize 3D Co-rich C/CoSi composite, but also demonstrates the decoration of Co can significantly enhance the OER performance of C/CoSi.