Work‐function‐induced Interfacial Built‐in Electric Fields in Os‐OsSe₂Heterostructures for Active Acidic and Alkaline Hydrogen Evolution

Abstract

Theoretical calculations unveil that the formation of Os‐OsSe2 heterostructures with neutralized work function (WF) perfectly balances the electronic state between strong (Os) and weak (OsSe2) adsorbents and bidirectionally optimizes the hydrogen evolution reaction (HER) activity of Os sites, significantly reducing thermodynamic energy barrier and accelerating kinetics process. Then, heterostructural Os‐OsSe2 is constructed for the first time by a molten salt method and confirmed by in‐depth structural characterization. Impressively, due to highly active sites endowed by the charge balance effect, Os‐OsSe2 exhibits ultra‐low overpotentials for HER in both acidic (26 mV @ 10 mA cm−2) and alkaline (23 mV @ 10 mA cm−2) media, surpassing commercial Pt catalysts. Moreover, the solar‐to‐hydrogen device assembled with Os‐OsSe2 further highlights its potential application prospects. Profoundly, this special heterostructure provides a new model for rational selection of heterocomponents.

d–p Orbital hybridization in RhSn catalyst boosts hydrogen oxidation reaction under alkaline electrolyte

“…During the positive-going process, the adsorbed CO species might be oxidized/desorbed with the adsorbed OH species and the poisoned catalytic sites will be reversibly recovered, leading to the possibility that the HOR current density of the first curve at higher potential (more than 0.30 V) and the current density of the second curve in the whole potential region will be recovered. 37,47–50 Expectedly, as for the second curves at a potential of 0.05 V, the current density of RhSn/C can be recovered to 97%, while that of Rh/C is merely recovered to 67%, compared to the original curve. On these bases, that RhSn/C delivering more distinct and reversible CO-tolerant property than Rh/C can be determined, which is related to its enhanced OH adsorption strength.…”

“…S19 and S20 †). 44,47 CO tolerance is also a critical characteristic of the HOR, on account of the probable presence of CO impurity in industrial H 2 supply. 41,44 Firstly, CO stripping experiments with RhSn/C and Rh/C were carried out, as displayed in Fig.…”

Designing a Built-In Electric Field for Efficient Energy Electrocatalysis

“…The HER kinetics significantly relies on the H + concentration in the electrolytes. In acidic media, rich H + are provided to adsorb onto the reaction sites and engage in the following steps, while an additional water dissociation is needed to produce protons in neutral and alkaline media for the subsequent steps, which generally serves as the rate-determining step for the neutral and alkaline HER. , As another vital half reaction, OER is the bottleneck of water splitting due to the more complicated electron transfer process and much larger reaction energy barrier than the HER. − The adsorbate oxygen evolution mechanism is widely accepted . Four consecutive proton–electron transfer steps occur on the metal active site in alkaline media: OH − + * → OH * + normale − OH * + OH − → O * + normalH 2 normalO + normale − O * + OH − → OOH * + normale − OOH * + OH − → normalO 2 + * + normalH 2 normalO + normale − …”

“…In acidic media, rich H + are provided to adsorb onto the reaction sites and engage in the following steps, while an additional water dissociation is needed to produce protons in neutral and alkaline media for the subsequent steps, which generally serves as the ratedetermining step for the neutral and alkaline HER. 97,98 As another vital half reaction, OER is the bottleneck of water splitting due to the more complicated electron transfer process and much larger reaction energy barrier than the HER. 99−102 The adsorbate oxygen evolution mechanism is widely accepted.…”

Engineering Multilevel Collaborative Catalytic Interfaces with Multifunctional Iron Sites Enabling High-Performance Real Seawater Splitting

“…In the era of environmental degradation and energy crises, hydrogen is the most ideal surrogate to substitute fossil fuels in future scenarios because of its high gravimetric energy density and near-zero carbon emission. − Given surplus renewable electricity derived from intermittent wind or solar energy, electrochemical water splitting is one of the promising and carbon-free apparatuses for green hydrogen production. − Among all the commercially available technologies, alkaline water electrolysis involving cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) is the most viable one due to its better compatibility with non-noble materials, but its energy conversion efficiency (200–400 mA cm –2 at 1.8–2.4 V in base) is greatly hindered by the low catalytic activities of hydrogen and oxygen-evolving electrocatalysts. ,− In this regard, various non-noble electrocatalysts have been developed to considerably ameliorate the energy conversion efficiency, ,,, such as transition metal phosphides, − nitrides, − selenides, , sulfides, , and so on. Despite the integrated merits of bifunctional catalysts in simplifying the device fabrication and reducing the preparation costs, only a few non-noble catalysts exhibit superb bifunctional catalytic properties for overall water splitting, probably due to the uncoordinated HER/OER activity. ,,,− For example, iron species are corroborated to have a great influence on expediting the OER reaction kinetics of the nickel or cobalt-based materials once hybridized with them, but nearly all the iron-based nonprecious electrocatalysts show poor HER activity in base due to the high kinetic energy barrier for initial water dissociation. , Thus, given that iron is the most earth-abundant transition metal with the lowest price, it is compelling but challenging to anchor iron species onto nickel or cobalt-based conductive supports, so as to construct high-performance bifunctional catalysts for electrocatalytic water splitting …”