Regulating Surface Charge by Embedding Ru Nanoparticles over 2D Hydroxides toward Water Oxidation

Exploring highly active and earth-abundant electrocatalystsforthe oxygen evolution reaction (OER) is considered one of the primeprerequisites for generating green hydrogen. Herein, a competent microwave-assisteddecoration of Ru nanoparticles (NPs) over the bimetallic layered doublehydroxide (LDH) material is proposed. The same has been used as anOER catalyst in a 1 M KOH solution. The catalyst shows an interestingRu NP loading dependency toward the OER, and a concentration-dependentvolcanic relationship between electronic charge and thermoneutralcurrent densities has been observed. This volcanic relation showsthat with an optimum concentration of Ru NPs, the catalyst could effectivelycatalyze the OER by obeying the Sabatier principle of ion adsorption.The optimized Ru@CoFe-LDH(3%) demands an overpotential value of only249 mV to drive a current density value of 10 mA/cm(2) withthe highest TOF value of 14.4 s(-1) as compared tosimilar CoFe-LDH-based materials. In situ impedance experiments andDFT studies demonstrated that incorporating the Ru NPs boosts theintrinsic OER activity of the CoFe-LDH on account of sufficient activatedredox reactivities for both Co and lattice oxygen of the CoFe-LDH.As a result, compared with the pristine CoFe-LDH, the current densityof Ru@CoFe-LDH(3%) at 1.55 V vs RHE normalized by ECSA increased by86.58%. First-principles DFT analysis shows that the optimized Ru@CoFe-LDH(3%)possesses a lower d-band center that indicates weaker and more optimalbinding characteristics for OER intermediates, improving the overallOER performance. Overall, this report displays an excellent correlationbetween the decorated concentration of NPs over the LDH surface whichcan tune the OER activity as verified by both experimental and theoreticalcalculations.

Automated summary

In this study, a microwave-assisted method is proposed to decorate Ru nanoparticles on a bimetallic layered double hydroxide material for the oxygen evolution reaction (OER) catalyst. The optimized Ru@CoFe-LDH(3%) shows a lower d-band center, indicating improved OER performance.