Oxygen Evolution Electrocatalysts for the Proton Exchange Membrane Electrolyzer: Challenges on Stability

Abstract

Hydrogen generated by proton exchange membrane (PEM) electrolyzer holds a promising potential to complement the traditional energy structure and achieve the global target of carbon neutrality for its efficient, clean, and sustainable nature. The acidic oxygen evolution reaction (OER), owing to its sluggish kinetic process, remains a bottleneck that dominates the efficiency of overall water splitting. Over the past few decades, tremendous efforts have been devoted to exploring OER activity, whereas most show unsatisfying stability to meet the demand for industrial application of PEM electrolyzer. In this review, systematic considerations of the origin and strategies based on OER stability challenges are focused on. Intrinsic deactivation of the material and the extrinsic balance of plant‐induced destabilization are summarized. Accordingly, rational strategies for catalyst design including doping and leaching, support effect, coordination effect, strain engineering, phase and facet engineering are discussed for their contribution to the promoted OER stability. Moreover, advanced in situ/operando characterization techniques are put forward to shed light on the OER pathways as well as the structural evolution of the OER catalyst, giving insight into the deactivation mechanisms. Finally, outlooks toward future efforts on the development of long‐term and practical electrocatalysts for the PEM electrolyzer are provided.

Design Strategies of Active and Stable Oxygen Evolution Catalysts for Proton Exchange Membrane Water Electrolysis

“…The performances of OER catalysts are evaluated and compared based on three key factors: intrinsic activity, extrinsic activity, and stability. ,, Intrinsic activity is primarily determined by the surface chemistry of the active metal species. This includes the electronic structure of the catalyst and adsorption and desorption energies of adsorbed intermediates involved in the OER .…”

“…Typically, the stability of the catalyst can be evaluated using cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP). Catalyst degradation has been attributed to atomic dissolution, oxygen vacancy formation via the LOM mechanism, lattice amorphization, and chemical instability under harsh acidic conditions. , These degradation pathways can be effectively suppressed by building a passivation layer and harnessing metal–support interactions.…”

“…Despite these advantages, the practical implementation of PEMWEs remains in its infancy. Toward the efficient and durable operation of PEMWE for industrial applications, the development of active and stable electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at the anode and cathode, respectively, is crucial. − However, the development of efficient and cost-effective OER electrocatalysts is particularly challenging; their activity is limited by intrinsically sluggish OER kinetics because the OER involves four proton-coupled electron transfers and multiple reaction intermediates. They often suffer from low stability because of the high operating potential and acidic environment required for the acidic OER.…”

Construction of a ruthenium-doped CoFe-layered double hydroxide as a bifunctional electrocatalyst for overall water splitting

“…S6, ESI†). 22,23 As to the high-resolution Ru 3p region of CoFe-ZLDH/Ru@NF (Fig. S7a, ESI†), two distinct peaks of Ru 3+ at 462.6 eV and 484.8 eV are assigned to Ru 3p 3/2 and 3p 1/2 .…”

Amorphous Oxysulfide Reconstructed from Spinel NiCo2S4 for Efficient Water Oxidation

“…[1,2] One of the key technologies for hydrogen production from renewable energy is electrochemical water splitting. [3][4][5][6] However, the anodic oxygen evolution reaction (OER) process with sluggish kinetics and high energy barriers have Wang's group [35] used cationic defect engineering to preferentially generate a large number of Co defects on spinel NiCo 2 O 4 . Theoretical calculations and experiments demonstrate that Al doping elongates the CoO bonds and promotes the ionization of Co under plasma treatment.…”