Partially hydroxylated ultrathin iridium nanosheets as efficient electrocatalysts for water splitting

Abstract

Two-dimensional (2D) materials have attracted considerable attention for their unique physicochemical properties and promising applications. However, the preparation of free-standing ultrathin 2D noble metal still remains a significant challenge. Here, for the first time we report a wet-chemical method to synthesize partially hydroxylated ultrathin Ir nanosheets (Ir-NSs) with only 5∼6 atomic layer thickness. Detailed analysis indicates that the growth confinement effect of carbon monoxide and partially hydroxylated surface play a critical role in the formation of ultrathin structure. The ultrathin Ir-NSs exhibit excellent performance for both hydrogen evolution reaction and oxygen evolution reaction in a wide pH range, outperforming the state-of-the-art Pt/C and IrO2, respectively. DFT calculations reveal that the partial hydroxylation not only enhances the surface electron-transfer between Ir-sites and intermediate O-species, but also guarantees an efficient initial activation of bond cleavage of H-O-H for first-step H2O splitting. This ultimately breakthroughs barrier of full water splitting with efficient electron-transfer essentially maintained.

Exclusive Strain Effect Boosts Overall Water Splitting in PdCu/Ir Core/Shell Nanocrystals

“…The normalized mass activities at 1.50 V (vs. RHE) further reveal the enhanced OER activity of the strained core/shell structure (Figure S7). The current overpotential and mass activity of PdCu/Ir/C represent one of the best level of the Ir‐based OER electrocatalysts in acidic conditions yet reported (Figure 2 e & Table S1) [29–38] …”

“…Thec urrent overpotential and mass activity of PdCu/Ir/C represent one of the best level of the Ir-based OER electrocatalysts in acidic conditions yet reported (Figure 2e &T able S1). [29][30][31][32][33][34][35][36][37][38] Stability,a so ne of the most important issues of electrocatalysts,i sa lso evaluated by accelerated durability tests (ADTs) and chronoamperometry (CP) measurement. After 2000 CV cycles between 1.40 and 1.65 V(vs.RHE) before IR correction at an accelerated scan rate of 50 mV s À1 ,t he overpotential of PdCu/Ir/C at acurrent density of 10 mA cm À2 only increases 5mV (Figure 2f).…”

Promotion effect of metal phosphides towards electrocatalytic and photocatalytic water splitting

“…On the one hand, bifunctional catalysts can be used for both the HER and OER; on the other hand, the use of bifunctional photocatalysts greatly reduces the cost of material preparation. Consequently, the design of bifunctional catalysts that are effective in an electrolyte for both the HER and OER is urgently needed 50,51 …”

Porous Structure Engineering of Iridium Oxide Nanoclusters on Atomic Scale for Efficient pH‐Universal Overall Water Splitting

“…Moreover, when paired with commercial 20 wt% Pt/C, P-IrO x @ DG can deliver current densities of 350.0, 317.6, and 47.1 mA cm −2 sites and unfavorable reconstruction during operation. [16][17][18] Embedding Ir by conductive carbon substrates like graphene and carbon nanotubes may improve the catalytic stability and intrinsic activity. [19] High-temperature pyrolysis and hydrothermal/solvothermal processes are commonly used to prepare metal composite/carbon hybrids.…”