Enhanced alkaline water splitting on cobalt phosphide sites by 4d metal (Rh)-doping method

• Published in: International journal of hydrogen energy Vol. 48; no. 58; pp. 22009 - 22020
• Main Authors: Perumal, Sakthivel, Seo, Junhyeok
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 08-07-2023
• Subjects: 4d and 5d metal doping; Alkaline water-splitting; Cobalt phosphide; Rhodium doping; Rhodium doping; Cobalt phosphide; 4d and 5d metal doping; Alkaline water-splitting
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2023.03.085

The construction of effective water-splitting electrocatalysts in alkaline conditions is challenging due to lower water dissociation efficiency than in acidic conditions. In this study, we investigated the effect of doping 4d and 5d metals into the 3d metal active site of cobalt phosphide (CoxP) on the water-splitting reaction. Introducing Ru slightly improved hydrogen evolution efficiency, but Rh doping significantly enhanced the catalytic parameters with an overpotential of 0.03 V at 10 mA/cm2. Rh regulated the electronic structure of CoxP to improve proton reduction. The Rh-CoxP electrode showed a comparable catalytic efficiency to that of a Pt/C standard. Ir doping slightly improved catalytic reactivity, but not as much as Rh. Our results showed that doping 4d metal from the same group as Co maximizes the doping effect during hydrogen evolution. A lab-scale water electrolyzer built with Rh-CoxP successfully demonstrated catalytic water splitting in alkaline electrolyte.
•We report the effect of 4d and 5d metal doping into the 3d metal active site.•The water splitting reaction by CoxP was used as a model reaction.•The 4d metal (Rh) dopant from the same group maximized the doping effect.•The Rh-CoxP electrode showed a comparable activity to a Pt/C standard.•A water electrolyzer working in alkaline media was successfully demonstrated.