In situ facile fabrication of ultrathin Co(OH)2-CoO/graphene oxide nanosheet hybrids with superior oxygen evolution reaction performance

As representative electrocatalysts for the oxygen evolution reaction (OER), Co-based hydroxides and oxides generally suffer from poor electron conductivity and severe self-agglomeration, substantially hindering their wide application in catalysis. To overcome such issues, we herein report a convenient electrostatic adsorption-assisted solvothermal method for the in situ fabrication of ultrathin Co(OH) ₂ -CoO/graphene oxide nanosheet hybrids (denoted as Co-O-H NSs/GO- x ) as efficient electrocatalysts for the OER in alkaline media. Notably, the optimal Co-O-H NSs/GO-1.4 mg sample with a thickness of 3.5–3.8 nm demonstrated outstanding electrocatalytic OER performance, with a low overpotential of only 283 mV at 10 mA cm ⁻² and a small Tafel slope of 57 mV dec ⁻¹ , making it comparable to state-of-the-art Co-based non-self-supporting electrocatalysts. Comprehensive analysis revealed that the superior OER electrocatalytic performance of Co-O-H NSs/GO-1.4 mg could be ascribed to the synergistic contribution from the enlarged electroactive surface area (approximately 146 mF.cm ⁻² for its double-layer capacitance), higher electron concentration (approximately 8.1 × 10 ¹⁷ cm ⁻³ ), enriched oxygen vacancies (accounting for approximately 74.3 % of the oxygen content) and the upshift of the 3d-band centre caused by the high-quality coupling between Co-O-H NSs and GO NSs. This work provides a universal synthetic strategy for the facile construction of high-performance hybrid nanosheet-based catalysts, showing particular importance for establishing efficient energy conversion reactions.