Abstract

Background: Increasing demand on the large scale H2 generation with the uttermost purity as required by the fuel cells is now totally depending on water splitting. The major energy consuming reaction in water splitting is the thermodynamically un-favoured oxygen evolution reaction (OER) for which the noble metal oxides such as IrO2 and RuO2 have so far been extensively used as efficient electrocatalysts. However, the increased metal dissolution at high anodic overpotential and expenses associated with these materials render its implementation in large scale H2 production. This report provides an alternative way of reducing the total RuO2 content with concomitantly increased corrosion resistance by alloying with NaPO3 at nano-scale.

Methods: A detailed research and review on the existing literature has been carried out. The synthesis was carried out utilizing conventional wet-chemical and thermal annealing routes. The same was then characterized in and screened as an electrocatalyst for OER in acidic electrolyte of pH 1.

Results: The successful synthesis of RuO2-NaPO3 nanocomposite was confirmed by various advanced characterizations such as XRD, HRTEM, XPS and EDS. Then the same was screened for acidic OER in comparison with the commercial catalyst RuO2 procured from Sigma. The results have shown that RuO2-NaPO3 nanocomposite required a very low overpotential of 250 mV at a current density of 10 mAcm-2 for which the commercial catalyst required 85 mV higher potential than RuO2- NaPO3 nanocomposite. Comparatively lower Tafel slope (110 mVdec-1) and minimum increase in overpotential at 10 mAcm-2 after cycling test for RuO2-NaPO3 nanocomposite had once again proven the advantages of alloying RuO2 with NaPO3 for harvesting synergistically enhanced OER activity with improved corrosion stability.

Conclusion: A comparatively easier synthesis of RuO2-NaPO3 nanocomposite enabled the use of RuO2 with comparatively reduced loading to harvest maximum catalytic efficiency. The intentionally incorporated NaPO3 had increased the catalytic performance of RuO2 and also increased the corrosion stability as revealed by the electrochemical characterizations. The proposed approach is undoubtedly adaptable for the fabrication of highly active other electrocatalysts for OER with improved corrosion stability.

Keywords: Core-shell nanostructures, oxygen evolution, overpotential, nanocatalyst, RuO2, Tafel analysis, water splitting.

Graphical Abstract