An Ir/Ni(OH)₂ Heterostructured Electrocatalyst for the Oxygen Evolution Reaction: Breaking the Scaling Relation, Stabilizing Iridium(V), and Beyond

Abstract

Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is highly challenging for hydrogen production from water splitting, due to the high energy barrier for OO bond formation and the restriction of the scaling relation between the multiple reaction intermediates. In order to simultaneously address these concerns, an Ir/Ni(OH)2 heterostructure with abundant heterointerfaces is deliberately designed as an efficient electrocatalyst system, with Ir nanoparticles (NPs) homogeneously confined on the Ni(OH)2 nanosheets. The strong electronic interaction and chemical bonding across the interface between the Ir and Ni(OH)2 can effectively stabilize the metastable electrophilic Ir(V) species, which is vital to boost the formation of OO bonds. Meanwhile, the adsorption of the multiple intermediates is synergistically optimized at the heterointerface, which breaks the restrictive scaling relation and substantially accelerates the OER kinetics. In addition, the severe agglomeration of Ir species is greatly mitigated by the confinement effect, ensuring the structural integrity of the catalyst and the constant exposure of active sites. Owing to its well‐defined multifunctional interfaces, the Ir/Ni(OH)2 heterostructure exhibits exceptional OER activity and durability in alkaline media. The present results highlight the significance of heterostructure interface engineering toward the rational design and development of advanced electrocatalysts for the OER and beyond.

The Effect of Cation Mixing in LiNiO2 toward the Oxygen Evolution Reaction

“…Previous studies have focused on Ni‐based oxides, including Ni(OH) 2 and doped NiOOH, due to their low material cost, easily mediated structure, and high OER activity originating from various dopants, making them promising catalysts to replace noble metal oxides [34–38] . Compared to Co‐containing perovskite‐type oxides, [22,39] relatively few studies correlating the electronic states of Ni‐based oxides with their OER activities have been reported.…”

“…Previous studies have focused on Ni-based oxides, including Ni(OH) 2 and doped NiOOH, due to their low material cost, easily mediated structure, and high OER activity originating from various dopants, making them promising catalysts to replace noble metal oxides. [34][35][36][37][38] Compared to Co-containing perovskite-type oxides, [22,39] relatively few studies correlating the electronic states of Ni-based oxides with their OER activities have been reported. Recent studies on nickel oxides have elaborated the doping effect of lithium on catalyst activity, [40,41] such as in LiNiO 2 where lithium doping changed the local electronic structure of nickel, improving OER activity.…”

Interface Engineering of Air Electrocatalysts for Rechargeable Zinc–Air Batteries

“…The adsorptions of these intermediates are correlated, and it is a formidable task to optimize the bonding strength simultaneously. [ 38 ] Interface engineering by combining catalysts with complementary activity together provides the opportunity to break such scaling law. It is noteworthy that the abovementioned effects do not operate separately, and as a rule, are directly or indirectly interrelated and together constitute the fundamentals of interface engineering.…”

“…Surprisingly, some previous work has demonstrated that such scaling law is possible to be broken by using synergistic effect arising from the heterointerface. [ 38 ] Sun et al. selectively combined the IrO 2 particles and Ni(OH) 2 nanosheets to form the heterostructure composite.…”

“…Surprisingly, some previous work has demonstrated that such scaling law is possible to be broken by using synergistic effect arising from the heterointerface. [38] Sun et al selectively combined the IrO 2 particles and Ni(OH) 2 nanosheets to form the heterostructure composite. Unlike the adsorption of OER intermediates was limited to a single active site, the intermediates OH* and O* were more likely to adsorb on Ni(OH) 2 / NiOOH and IrO x , respectively.…”