Rational strain engineering in delafossite oxides for highly efficient hydrogen evolution catalysis in acidic media

Abstract

The rational design of hydrogen evolution reaction (HER) electrocatalysts which are competitive with platinum is an outstanding challenge to make power-to-gas technologies economically viable. Here, we introduce the delafossites PdCrO 2 , PdCoO 2 and PtCoO 2 as a new family of electrocatalysts for the HER in acidic media. We show that in PdCoO 2 the inherently strained Pd metal sublattice acts as a pseudomorphic template for the growth of a strained (by +2.3%) Pd rich capping layer under reductive conditions. The surface modification continuously improves the electrocatalytic activity by simultaneously increasing the exchange current density j 0 from 2 to 5 mA/cm² geo and by reducing the Tafel slope down to 38 mV/decade, leading to overpotentials 10 < 15 mV for 10 mA/cm² geo , superior to bulk platinum. The greatly improved activity is attributed to the in-situ stabilization of a β-palladium hydride phase with drastically enhanced surface catalytic properties with respect to pure or nanostructured palladium. These findings illustrate how operando induced electrodissolution can be used as a top-down design concept for rational surface and property engineering through the strainstabilized formation of catalytically active phases.

Recent Progress of Vacancy Engineering for Electrochemical Energy Conversion Related Applications

“…[ 119 ] Various strategies have been applied to boost catalytic activity of nonprecious composites, such as doping, [ 116c,120 ] specific nanostructure, [ 121 ] and other techniques. [ 122 ] Recently, ionic vacancies, including anodic vacancies, cationic vacancies, and mixed vacancies, have been explored for HER with satisfactory electrocatalytic activity. [ 64,123 ] Promising results indicate the great potential of vacancies on promoting electrocatalytic performance ( Table 2 ).…”

Exploiting Ru‐Induced Lattice Strain in CoRu Nanoalloys for Robust Bifunctional Hydrogen Production

“…[21,22] Alloying TMs has many benefits,such as lower catalyst cost, optimization of electronic properties through induced strain effects,a nd different adsorption strengths of key reaction intermediates,all of which can boost catalytic activity at the atomic scale. [23][24][25] Cobalt (Co) is an abundant low-cost transition metal that is widely used in the hydrolysis of AB.However,metallic Co has poor HER catalytic activity due to its weak hydrogen bonding energy. [26][27][28] In contrast, the noble metal ruthenium (Ru) is an ideal HER catalysts,w ith the cost of Ru being approximately 1/3 that of Pt.…”

“…Accordingly, more and more attention is now being paid to transition metals alloy‐based catalysts [21, 22] . Alloying TMs has many benefits, such as lower catalyst cost, optimization of electronic properties through induced strain effects, and different adsorption strengths of key reaction intermediates, all of which can boost catalytic activity at the atomic scale [23–25] …”

Favorable Amorphous−Crystalline Iron Oxyhydroxide Phase Boundaries for Boosted Alkaline Water Oxidation

“…In light of rapid fossil fuel consumption, severe environmental pollution, and drastic climate change, hydrogen (H 2 ) evolution technologies are paid more attention, owing to the high energy density and environmental‐friendliness of H 2 . Among them, electrochemical water splitting (2H 2 O→2H 2 +O 2 ), as a well‐established and renewable‐driven electrolysis process, has tremendous potential for converting electricity from the intermittent sun, wind, and other renewable sources into clean chemical energy (H 2 ) . Although many studies have been reported, a huge challenge facing this scenario remains the design of highly efficient catalyst electrodes to improve sluggish kinetics of the oxygen evolution reaction (OER) .…”