Importance of Water Structure and Catalyst–Electrolyte Interface on the Design of Water Splitting Catalysts

Abstract

Hydrogen production technologies have attracted intensive attention for their potential to cope with future challenges related to renewable energy storage and conversion. However, the significant kinetic barriers associated with the oxygen evolution reaction (OER), one of the two half reactions at the heart of water electrolysis, greatly hinder the sustainable production of hydrogen at a large scale. A wide variety of materials have thus been designed and explored as OER catalysts. In this perspective, we briefly review the development of Ir-based OER catalysts in acidic conditions and discuss the limitations of a design strategy solely based on the physical and electronic properties of OER catalysts, highlighting the importance of understanding the catalystelectrolyte interface which affects the stability and activity of the catalyst. We then share our perspective on a group of crystalline, bulk protonated iridates obtained via cation exchange in acidic solutions to be used as promising stable and active OER catalysts. Finally, we discuss the advances recently made in understanding the impact of the active sites environment on the OER kinetics, emphasizing the influence of the water structure and/or solvation properties of ions in the electrolyte. We highlight the importance of developing a better understanding of these influencing factors and incorporate them into our design of OER catalysts with enhanced properties.

Revealing the Impact of Electrolyte Composition for Co-Based Water Oxidation Catalysts by the Study of Reaction Kinetics Parameters

“…This observation is in agreement with a previous report by Bockris and Otagawa who found a linear trend between the OER activity and the activation energies measured for a wide variety of perovskites, as we recently discussed. 42,43 Now turning to the evolution of the apparent pre-exponential factor as a function of the OER activity, it is found to decrease concomitantly to the decrease of the activation energies. While the decrease of the apparent pre-exponential factor should result in a decrease of the OER activity (equation 3b), the effect associated with the decrease of the activation energy is predominant on the OER kinetics for these perovskites.…”

First Example of Protonation of Ruddlesden–Popper Sr2IrO4: A Route to Enhanced Water Oxidation Catalysts

“…Unlike the 2D RP phase, the H + /Sr 2+ exchange in cubic or hexagonal perovskite such as SrIrO 3 would introduce significant lattice strain on the 3D IrO 6 -network and thus compromise the structural integrity of the parent phase, leading to a dissolution of the phase and a precipitation of amorphous IrO x compounds on its surface. 18 30 which consists of trigonal layers of edgesharing octahedra.…”

Recent Development of Oxygen Evolution Electrocatalysts in Acidic Environment

“…They further pointed out that the OER performance of the above-mentioned perovskites is eventually dominated by the electrochemically deposited IrO x •mH 2 O at their surfaces, rather than the perovskites themselves. [154,155] Similarly, with Ir(111), Ir (210), and Ir(210) as planar models, Maillard and co-workers concluded that surface oxidation trends to be a more stable one, which may be not related to the original surface atoms arrangement and oxidation state. [153] Figure 10.…”

“…; 779 A g Ru+Pt −1 @1.51 V 28 h@10 mA cm −2 Pd@Ir3L [90] 0.1 m HClO 4 263 mV @10 mA cm −2 3.33 A mg Ir [174] 0.5 m H 2 SO 4 270 mV @10 mA cm −2 800-1600 A g Ru Co-RuIr alloy [104] 0.1 m HClO 4 235 mV @10 mA cm −2 solvation on the OER activity of catalysts. [155] Furthermore, more theoretical studies and experiment measurements are required to reveal the mechanisms of electrode-electrolyte interfaces for designing better catalysts for OER in acid.…”