Engineering Porous Carbon Nitride: Sub-Nanometer Ni/Co Functionalization for Highly Robust Oxygen Evolution Reaction

Abstract

Efficient and sustainable water electrocatalysis requires a stable and effective OER catalyst that is derived from low-cost and earth-abundant sources. This work involves the use of a simple ultrasound nanopore-confinement method to grow highly dispersed Ni/Co catalysts on a porous carbon nitride (PCN) network having a large surface area using a single source precursor for carbon/nitrogen source. This process successfully restricts the growth of metal catalysts to sub- 1 nm. The good dispersion of the metal components on the PCN support was confirmed using HRTEM, HAADF-STEM, and elemental mapping images. The structure of the catalyst was characterized using XRD and XPS. Incorporating Ni or Co into PCN significantly reduces the OER overpotential to achieve 10 mAcm-2 compared to the pristine PCN network, with the overpotential of 245 mV (vs. RHE) for Co-f-PCN, 255 mV (vs. RHE) for Ni-f-PCN, and 310 mV (vs. RHE) for PCN. The small Tafel slope values of the three catalysts (PCN~ 67.8 mV/dec; Co-f-PCN ~ 44.22 mV/dec and Ni-f-PCN ~ 46.8 mV/dec) indicate that incorporating Ni or Co into PCN enhances the OER. Furthermore, the PCN, Co-f-PCN, and Ni-f-PCN catalysts demonstrated exceptional long-term durability, with only a minimal attenuation of about 4% after 24 hours. This method allows the integration of Ni or Co into the PCN network with a high N content and a high surface area, significantly enhancing electrocatalytic OER activity and conductivity.