Improved OER Catalytic Performance of NiFe-LDH with Hydrothermal Carbonization Microspheres

The electrochemical oxygen evolution reaction (OER) is a fundamental anodic semi-reaction used in the hydrogen energy industry. Herein, we report a novel NiFe-layered double hydroxide (NiFe-LDH)-based hybrid catalyst for the OER, which is promoted by the two-step hydrothermal loading of carbon sphere (CS) onto NiFe-LDH sheets, named as NiFe-LDH@CS. The effects of hydrothermal carbonization (HTC) parameters (such as hydrothermal time and glucose concentration) and the loading ratio of CSs on NiFe-LDH@CS were investigated. The results showed that the two-step hydrothermal synthesis significantly inhibited the interference of the carbonized substances on the lattice formation of NiFe-LDH and successfully achieved a firm combination. By adjusting the HTC process, the surface char-acteristics and graphitization degree of the carbonized microspheres can be effectively controlled, leading to increased OER performance of NiFe-LDH@CS. Thus, under the optimal process parameters (5 h, 0.6 M, and 5 mL), NiFe-LDH@CS exhibited an excellent overpotential of 292 mV at 50 mA cm-2 and 372 mV at 100 mA cm-2 for the OER. The outstanding OER performance of NiFe-LDH@CS is attributed to the excellent morphology control of the composite, abundant functional groups, and suitable graphi-tization degree of the hydrothermally carbonized CS, as well as the synergistic effect between the CSs and NiFe-LDH. (c) 2023 Elsevier B.V. All rights reserved.