Interface‐ and Surface‐Engineered PdO−RuO₂ Hetero‐Nanostructures with High Activity for Hydrogen Evolution/Oxidation Reactions

Abstract

Active catalysts for HER/HOR are crucial to develop hydrogenbased renewable technologies. The interface of hetero-nanostructures can integrate different components into a single synergistic hybrid with high activity. Here, the synthesis of PdOÀ RuO 2 À C with abundant interfaces/defects was achieved for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR). It exhibited a current density of 10 mA cm À 2 at 44 mV with a Tafel slope of 34 mV dec À 1 in 1 m KOH. The HER mass activity was 3 times higher in base and comparable to Pt/C in acid. The stability test confirmed high HER stability. The catalyst also exhibited excellent HOR activity in both media; in alkaline HOR it outperformed Pt/C. The exchange current density i 0,m of PdOÀ RuO 2 /C was 522 mA mg À 1 in base, which is 58 and 3.4 times higher than those of Pd/C and Pt/C. The HOR activity of PdOÀ RuO 2 /C was 22 and 300 times higher than those of PdO/C in acid and base. Improve-ment of HER/HOR kinetics in different alkaline electrolytes was observed in the order K + < Na + < Li + , and increase of HER as well decrease of HOR kinetics was observed with increasing Li + concentration. It was proposed that OH ad -M + -(H 2 O) x in the double-layer region could influence HER/HOR activity in base. Based on the hard and soft acid and base (HSAB) theory, the OH ads -M + -(H 2 O) x could help to remove more OH ads into the bulk, leading to increase in HER/HOR activity in alkaline electrolyte (K + < Na + < Li + ) and increasing the HER with increasing Li + concentration. The decrease of HOR activity of PdOÀ RuO 2 /C with increasing M + was due to M + -induced OH ads destabilization through the bifunctional mechanism. The high HER/HOR activity of PdOÀ RuO 2 /C could be attributed, among other factors, to interface engineering and strong synergistic interaction. This work provides an opportunity to design oxidebased catalysts for renewable energy technologies.

Bias-induced surface reconstruction of a MOF-derived bimetallic (Co & V) oxide as an electrocatalyst for water oxidation

“…S8 and S9†). 50 Thus, the results of FESEM and TEM revealed that self-surface modification occurred during the course of the electrolysis. 31 The ICP-OES studies of the elute of the post catalyst confirmed that almost 70% of vanadium was leached into the solution (Table S5†), which led to an increase in the surface area of the material and exposed more and more active sites for the catalytic process.…”

RuO 2 as promoter in Pt‐RuO 2 ‐ nanostructures/carbon composite, a pH ‐universal catalyst for hydrogen evolution/oxidation reactions

“…The i 0,m and i 0,s values for RuO 2 ‐Pt/C in 0.1 M KOH are 1833 mA/mg Pt,Ru and 1.8 mA/cm 2 Pt,Ru respectively. The HOR activity of RuO 2 ‐Pt/C was far better over Pt‐based reported catalysts in base media 51‐59 . For example, J. Zheng et al 50 reported i 0 value for Pt disk electrode was 0.21 mA.cm −2 in 0.1 M KOH.…”

“…The HOR activity of RuO 2 -Pt/C was far better over Pt-based reported catalysts in base media. [51][52][53][54][55][56][57][58][59] For example, J. Zheng et al 50 reported i 0 value for Pt disk electrode was 0.21 mA.cm À2 in 0.1 M KOH. The i 0,m value of RuO 2 -Pt/C in 0.1 M KOH is 29 and 8-fold higher than Ru-Pt-NPs/C and comm Pt/C respectively.…”

Interfacial Electronic Coupling of NC@WO3‐W2C Decorated Ru Clusters as a Reversible Catalyst toward Electrocatalytic Hydrogen Oxidation and Evolution Reactions

“…[1d] However, PEMFCs operate in a strong acidic condition and rely on expensive Ptbased catalysts. [4] As a result; alkaline anion-exchange membrane fuel cells (AAEMFCs) and water electrolyzers have been regarded as a promising alternatives to the PEMFC-based devices. [5] Subsequently, the rapid development of AAEMFCs has motivated searches for active HOR/HER electrocatalysts in alkaline conditions.…”

“…[12] Samanta et al showed that HBE and oxophilic property may play equally important roles for HOR/HER in the alkaline medium. [4] Meanwhile, Speck et al demonstrated that maximizing the metal and metal oxide interface is crucial to HOR activity. [8d] Ruthenium is considered as an alternative to Pt in HOR/HER catalysts owing to the appropriate strength of RuÀ H bonds and lower price.…”