Rhodium‐Modified Glassy Carbon Electrode as a Promising Electrocatalyst for Oxygen Reduction Reaction in Phosphoric Acid Electrolytes

Abstract A low‐cost glassy carbon electrode (GCE), modified with minimum amount of noble metal rhodium (Rh) via electrodeposition method can sensibly enhance the electrocatalytic oxygen reduction reaction (ORR) in H 3 PO 4 solution (pH∼2.0). The successful Rh electrodeposition was confirmed by using field emission scanning electron microscopy (FE‐SEM) and X‐ray photoelectron microscopy (XPS). The rotating disk electrode (RDE) technique was used in kinetic investigation to confirm the ORR mechanism followed by the 4e − transfer process, resulting in the production of water as the final product on the Rh‐GCE surface. This finding was further supported by rotating ring disk electrode (RRDE) analysis. The transfer coefficient (α) value was determined ∼0.36, indicated the protonation and electron transfer process in the rate‐limiting step of the ORR followed a concerted pathway. The exchange current density ( j 0 ) and standard rate constant ( k o ) were determined to be 1.09 × 10 −4 A cm −2 and 2.35 × 10 −4 cm s −1 , respectively.