Hydrogen spillover inspired bifunctional Platinum/Rhodium Oxide-Nitrogen-Doped carbon composite for enhanced hydrogen evolution and oxidation reactions in base

• Published in: Journal of colloid and interface science 2024-09, Vol.670, p.258-271
• Main Authors: Kumar Manna, Biplab, Samanta, Rajib, Kumar Trivedi, Ravi, Chakraborty, Brahmananda, Barman, Sudip
• Format: Article
• Language: English
• Subjects: Activation Energy; Bi-functional; carbon; Density Functional Theory; dissociation; Electrical Double Layer; energy; fuels; HBE/OHBE; hydrogen; hydrogen production; Hydrogen-spillover; Interfaces; oxidation; platinum; renewable energy sources; rhodium; species; Work-function
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2024.05.101

A facile synthesis of Pt-Rh2O3/CNx composite is reported for superior electrocatalytic hydrogen evolution and oxidation reaction (HER/HOR) in base. The HER/HOR performance of Pt-Rh2O3/CNx is ∼6/3.4 times better than commercial Pt/C. Both the hydrogen and hydroxyl binding energy are equal descriptors for alkaline HER/HOR. The hydrogen spillover from Pt to Rh2O3 enhances the HER/HOR performance. The role of hydroxyl-metal-water species on alkaline HOR was also discussed. [Display omitted] •The Platinum/Rhodium Oxide-Nitrogen-Doped Carbon (Pt/Rh2O3-CNx) nanocomposite was prepared for bifunctional HER/HOR in base media.•The HOR/HER activities of Pt/Rh2O3-CNx are ∼ 3.5/6 times higher than commercial Pt/C.•Experimental, theoretical studies suggest H-spillover increases catalytic activity.•HBE and OHBE are responsible for alkaline HER/HOR; a bifunctional mechanism was proposed.•Interfaces, porosity, ECSA, and synergetic interactions also helped for high activity. The poor activity of Pt-based-catalysts for alkaline hydrogen oxidation/evolution reaction (HOR/HER) encourages scientific society to design an effective electrocatalyst to develop alkaline fuel cells/electrolyzers. Herein, platinum/rhodium oxide-nitrogen-doped carbon (Pt/Rh2O3-CNx) composite is prepared for alkaline HER and HOR inspired by hydrogen spillover. The HER performance of Pt/Rh2O3-CNx is ∼ 6 times higher than Pt/C. In HOR, Pt/Rh2O3-CNx possesses an exchange current density of 657.60 mA/mgmetal, which is ∼ 3.4 times higher than Pt/C. Hydrogen and hydroxyl binding energy (HBE and OHBE) contribute equally to alkaline HOR/HER. The experimental and theoretical evidence suggests that the enhanced HER and HOR activity of Pt/Rh2O3-CNx may be due to hydrogen spillover from Pt to Rh2O3. Small work function difference [0.08 eV] of the system suggested hydrogen-spillover is feasible, which has been justified by reaction-free energy calculations. We proposed that the dissociation of hydrogen (H2) and water (H2O) occurs at Pt to form Pt-adsorbed hydrogen species (Pt-Had). Then, some Had moves to Rh2O3 through hydrogen spillover and reacts with neighboring Had or adsorbed hydroxyl species (OHad) to form H2 or H2O, which enhances the HER and HOR activity, respectively. The role of water-metal-hydroxyl species in the electrical double layer was also demonstrated on alkaline HOR/HER. This work may help to design the hydrogen-spillover-based catalysts for several renewable energy technologies.