Trifunctional catalytic performance of cobalt, praseodymium, and neodymium decorations on porous graphitic carbon nitride/CNT composites for HER, OER, and ORR

This study presents the synthesis of various metal-decorated porous graphitic carbon nitride and carbon nanotube composite (PCN-CNT) aimed at investigating their catalytic performance through the oxygen reduction and evolution and hydrogen evolution reactions, as the key reactions in several energy conversion and storage technologies. Praseodymium, neodymium and cobalt are incorporated into the PCN-CNT composite in single forms (Co@PCN-CNT, Pr@PCN-CNT, Nd@PCN-CNT) and binary forms (Pr-Co@PCN-CNT, Nd-Co@PCN-CNT). Morphological and physiochemical characterization analyses confirm the successful formation and mesoporous structure of the catalyst material. Electrochemical analyses show an enhanced performance of the double metal catalysts compared to their single metal cases, owing to their synergetic effects. Nd-Co@PCNT-CNT shows a promising catalytic performance towards ORR (onset potential of 0.917 V , half-wave potential of 0.747 V vs RHE), while Pr-Co@PCN-CNT shows the best OER activity (overpotential of 295 mV at 10 mA/Cm 2 ). HER shows moderate values for Nd-Co@PCN-CNT (overpotential of 199 mV at −10 mA/cm 2 ). The findings show the potential of double-metal PCN-CNT composite catalysts as low-cost and efficient alternatives to precious-metal catalysts. • Bimetallic PCN-CNT catalysts decorated with Pr, Nd, and Co metals. • Double metal catalysts show superior ORR, OER, and HER activity. • Nd-Co@PCN-CNT exhibits excellent ORR performance with low onset potential. • Pr-Co@PCN-CNT achieves enhanced OER efficiency with stable overpotential. • Electrochemical analysis confirms synergy in bimetallic catalysts.