biostudies-literatureCheng ZMinistry of Science and TechnologyJiangsu Province Natural Science Fund for Distinguished Young ScholarsNational Natural Science Foundation of China1340-1348https://www.ebi.ac.uk/biostudies/studies/S-EPMC8288892biostudies-literatureUnknown7(8)Ultrathin two-dimensional (2D) materials have attracted considerable attention for their unique physicochemical properties and promising applications; however, preparation of freestanding ultrathin 2D noble metal remains a significant challenge. Here, for the first time, we report use of a wet-chemical method to synthesize partially hydroxylated ultrathin Ir nanosheets (Ir-NSs) of only five to six atomic layers' thickness. Detailed analysis indicates that the growth confinement effect of carbon monoxide and the partially hydroxylated surface play a critical role in formation of the ultrathin structure. The ultrathin Ir-NSs exhibit excellent performance for both the hydrogen evolution reaction and oxygen evolution reaction in a wide pH range, outperforming the state-of-the-art Pt/C and IrO₂, respectively. Density-functional theory calculations reveal that the partial hydroxylation not only enhances the surface electron transfer between Ir-sites and intermediate O-species, but also guarantees efficient initial activation of bond cleavage of H-O-H for first-step H₂O splitting. This, ultimately, breaks through barriers to full water splitting, with efficient electron transfer essentially maintained.National science reviewPartially hydroxylated ultrathin iridium nanosheets as efficient electrocatalysts for water splitting.PMC82888922017YFA0208200215711352016YFA0204100BK20170003Pi YHuang XHuang BLi LShao QCheng ZfalsePartially hydroxylated ultrathin iridium nanosheets as efficient electrocatalysts for water splitting.Ultrathin two-dimensional (2D) materials have attracted considerable attention for their unique physicochemical properties and promising applications; however, preparation of freestanding ultrathin 2D noble metal remains a significant challenge. Here, for the first time, we report use of a wet-chemical method to synthesize partially hydroxylated ultrathin Ir nanosheets (Ir-NSs) of only five to six atomic layers' thickness. Detailed analysis indicates that the growth confinement effect of carbon monoxide and the partially hydroxylated surface play a critical role in formation of the ultrathin structure. The ultrathin Ir-NSs exhibit excellent performance for both the hydrogen evolution reaction and oxygen evolution reaction in a wide pH range, outperforming the state-of-the-art Pt/C and IrO₂, respectively. Density-functional theory calculations reveal that the partial hydroxylation not only enhances the surface electron transfer between Ir-sites and intermediate O-species, but also guarantees efficient initial activation of bond cleavage of H-O-H for first-step H₂O splitting. This, ultimately, breaks through barriers to full water splitting, with efficient electron transfer essentially maintained.2020-01-01T00:00:00Z2020 Aug2024-11-21T07:36:16.945Z2024-11-21T07:36:16.945ZS-EPMC82888923469216210.1093/nsr/nwaa058