Development of activated carbon/bimetallic transition metal phosphide composite materials for electrochemical capacitors and oxygen evolution reaction catalysis

Pinecone-derived activated carbon (AC) and bimetallic transition metal phosphide (TMP) composites were produced and utilized as electrochemical capacitor (EC) electrodes and oxygen evolution reaction (OER) catalysts in this study. The base transition metal (TM) was Ni for all samples, and the secondary TM was one of Fe, Mn and Co. AC serves as a porous structure for double layer formation and active sites for OER catalysis. Bimetallic TMP is utilized due to redox reactions in EC and catalytic activity in OER. It is ascertained that secondary TM affects both EC and OER catalysis properties since they introduce multiple redox sites and alter the electronic configuration. As a result, Co is found to be beneficial for EC applications as a secondary TM, while Fe and Mn are shown to improve OER catalysis performance significantly. NiFeP and NiMnP-based composite have 44 mV/dec Tafel slopes and 313 and 316 mV overpotentials, respectively.