Pd-Modified CoP and CoFeP Catalysts as Efficient Bifunctional Catalysts for Water Splitting

Developing highly efficient and stable electrocatalysts from inexpensive and earth-abundant elements represents a significant advancement in the overall water splitting (OWS) process. This study focuses on the synthesis and evaluation of palladium-modified cobalt-phosphorus (PdCoP) and cobalt-iron-phosphorus (PdCoFeP) coatings for use as electrocatalysts in the HER, OER and OWS in alkaline media. For this purpose, a facile electroless plating method is adopted to deposit the CoP and CoFeP coatings onto a copper surface (Cu sheet), with sodium hypophosphite (NaH2PO2) acting as the reducing agent. Incorporating Pd crystallites on the CoP and CoFeP coatings using the galvanic displacement method has been shown to significantly improve catalytic performance. Accordingly, Pd modified CoFeP and CoP catalysts exhibited the lower overpotentials of 207 and 227 mV, respectively, for HER and 396 mV for OER at a current density of 10 mA cm−2 compared to the unmodified CoFeP and CoP catalysts. Simultaneously, the assembled electrolyzer comprising PdCoFeP as the cathode and the anode demonstrated a cell voltage of 1.69 V to achieve 10 mA cm−2. This study demonstrates that all the synthesized catalysts (CoP, CoFeP, PdCoP, and PdCoFeP) are effective and stable electrocatalysts for overall alkaline water splitting.