Interfacial design strategy for layered Co(OH)2/rGO catalysts toward high-performance oxygen evolution reaction

Co(OH) 2 nanosheets have a layered structure with a large specific surface area and favorable electronic properties for the adsorption and desorption of oxygen intermediates. This makes them promising electrocatalysts for the oxygen evolution reaction (OER) in water electrolysis. However, the intrinsically sluggish kinetics of the OER lead to high overpotentials, which necessitates the development of efficient catalysts. Herein, a sandwich-like Co(OH) 2 /rGO layered structure was constructed by integrating Co(OH) 2 nanosheets with reduced graphene oxide (rGO) via a spray-assisted layer-by-layer assembly method. The layered structure increased the interfacial conductivity and shortened the electron transport pathways, while the conductive rGO network and abundant Co(OH) 2 active sites synergistically increased the catalytic activity. Consequently, the Co(OH) 2 /rGO layered structure exhibited an overpotential of 385 mV at 10 mA cm -2 with a Tafel slope of 81 mV dec -1 in 1 M KOH, along with a rapid OER onset at approximately 1.50 V vs RHE. Electrochemical impedance spectroscopy showed that the charge-transfer resistance was significantly reduced, indicating that the interfacial electron transport was improved compared to that in single-component nanosheets. These findings demonstrate that layer-by-layer interfacial engineering of two-dimensional nanosheets provides an effective strategy for enhancing OER electrocatalytic performance. • A sandwich-like Co(OH) 2 /rGO layered structure was fabricated as an electrocatalyst • Using spray-assisted assembly, Co(OH) 2 and rGO nanosheets were stacked alternately • Electrocatalytic performance was evaluated for the oxygen evolution reaction (OER) • Co(OH) 2 /rGO lowered the overpotential of the OER and increased the current density • Interfacial engineering successfully improved the electrocatalytic performance