Intermetallic Rhodium Alloy Nanoparticles for Electrocatalysis

Abstract

The rational design and facile synthesis of highly activated and stable electrocatalysts toward the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR) are extremely demanded but remain challenging. Herein, a highly efficient bifunctional electrocatalyst composed of rhodium (Rh), cobalt (Co), and iron (Fe) alloy nanoparticles embedded in nitrogen-doped graphene (RhFeCo@NG) is prepared through sequential annealing and the substitution reaction. The as-prepared Rh2.6Fe3Co2.6@NG electrocatalyst achieves an overpotential as low as 25 mV for reaching a current density of 10 mA cm–2 and an ultralow Tafel slope of 29.8 mV dec–1 in 1 M KOH solution for HER, which is even superior to the state-of-the-art platinum (Pt) catalyst. With regard to ORR, for the Rh2.6Fe3Co2.6@NG electrocatalyst, a half-wave potential (E 1/2) of 0.82 V versus reversible hydrogen electrode and excellent long-term stability are achieved. The experimental results illustrate that alloying the Rh atom with the FeCo nanoalloy is mainly responsible for the excellent HER and ORR performances. This study not only provides a robust and promising electrocatalyst for HER and ORR in alkaline media but also sheds light on the devising of efficient and multifunctional catalysts.

Progress in electrocatalytic hydrogen evolution of transition metal alloys: synthesis, structure, and mechanism analysis

“…The synthesis of HEAs is different from that of binary and ternary alloys because of the immiscibility between metals. Component regulation 1 M KOH 28 20 mA cm −2 for 12 h 52.1 MoO x -FeCoCu 167 Hybridizing engineering 1 M KOH 197 10 mA cm −2 for 25 h 121.9 Rh 2.6 Fe 3 Co 2.6 @NG 168 Hybridizing engineering 1 M KOH 25 20 mA cm −2 for 10 h 29.8 hcp-RuIrPt 169 Phase engineering 1 M KOH 9.4 10 000 cycles 22.3 Reproduced with permission. 166 Copyright 2020, American Chemical Society.…”

Reasonably constructed nano-alloyed materials as highly efficient electrocatalysts for the hydrogen evolution reaction

“…In HER electrocatalysts with a core–shell nano-alloy structure, core–shell composite materials with alloy nanoparticles encapsulated within the carbon matrix are the focus of research, and the choice of carbon carrier is mainly nitrogen-doped carbon. 4,45,46,62,78,81,82,91,115–117 The activity is mainly attributed to the interfacial charge transfer from the metal core to the carbon shell, which manipulates the electronic interactions between the catalyst surface and reaction intermediates, and varies with the structures and morphologies of the metal core (elemental composition, core size, etc. ) and carbon shell (doping, layer thickness, etc.…”

Rh for HER electrocatalysis? A critical analysis of recent studies and thoughts on the same!

“…In most cases, the ‘go to’ second metal had been Pt, which is justifiable because the latter is the best in the business. An example of this multimetallic alloy of Rh is the work of Jiang and co-workers 50 who made the RhCoFe intermetallic alloy and wrapped it using N-doped graphenes (NGs). The synthesis was a two-step method that involved the synthesis of CoFe metallic nanocubes following the well-known Prussian blue analog (PBA) fabrication method, which was then alloyed with Rh by stirring the same with an Rh 3+ solution which replaced both Fe and Co to its molar proportion and formed the RhFeCo@NG intermetallic alloy that performed well in alkaline HER by requiring low overpotentials and Tafel slope when compared to the controls and Pt/C (Fig.…”