Sub-2 nm IrO2/Ir nanoclusters with compressive strain and metal vacancies boost water oxidation in acid

Reducing the Ir−O Coordination Number in Anodic Catalysts based on IrOx Nanoparticles towards Enhanced Proton‐exchange‐membrane Water Electrolysis

“…Figure S10c–d shows that the Bode diagram at low‐frequency changes abruptly, showing that the phase angle decreases with the increase of applied potential. At 1.5 V, the phase angle of IrO x is smaller than that of rutile‐IrO 2 , which indicates that IrO x has more electronic participation in the OER process [20] …”

“…Among them, the peak‐area percentage of O −OH can reach up to 55.03 % in amorphous IrO x , much larger than that in rutile‐IrO 2 (i.e., 32.01 %). Since the O −OH is an electrophilic oxygen species, such a higher content would promote electron transfer during the OER process [20] . On the other hand, in XAS spectra, amorphous IrO x showed a shift of Ir L 3 ‐edge to higher energy compared to rutile‐IrO 2 (Figure 3d), indicating its higher valence state of Ir species [23] .…”

“…On the other hand, EXAFS spectra show that the Ir−O bond length at the low‐coordinated samples is shortened from 1.66 Å to 1.6 Å as the OCV increased up to 1.6 V ( vs . RHE), in sharp contrary to unchanged bond length at rutile‐IrO 2 , which could effectively adjust the d‐band center and electronic structure of IrO 2 , causing a good affinity of the active site to oxygenate intermediates [20] . This behavior would arise from randomly connected octahedrons [IrO 6 ] in low‐coordinated IrO 2 , potentially making Ir species easier to oxidize in the oxidation‐reduction process [13] …”

Lattice Strain and Surface Activity of Dislocation‐Distorted AgPd Nanoalloys Under Preoxidation and Catalysis Condition

“…[ 24 ] The hd‐AgPd Ns with ‐5% strain is closest to the Fermi level among the three models, indicating that the electronic structure is related to the modification of strain. [ 25 ] Figure S13, Supporting Information, shows the calculated state densities and d‐band centers of Pd and Ag NPs under the same conditions as hd‐AgPd NPs. The positive shift in the d‐band center of hd‐AgPd NPs suggests that partial surface electrons of Ag transfer to Pd.…”

Ultralow-iridium content NiIr alloy derivative nanochain arrays as bifunctional electrocatalysts for overall water splitting

“…This excellent OER activity may be attributed to both the interfacial effect between the surface Ni(OH) 2 /IrO 2 thin lm and the beneath metallic NiIr x core, which facilitates the charge transfer from the (hydr)oxide shell to the metallic NiIr x core, and the synergistic effect between Ni 2+ and Ir 4+ in the (hydr) oxide shell, which can regulate the local electronic conguration to optimize the adsorption and desorption energy of the OER intermediates. [45][46][47][48][49][50] In contrast, although there is also an interface formed by Ni(OH) 2 and Ni in NiIr 0 NCs, Ir is missing and thus results in a lack of synergistic enhancement and the poor conductivity of Ni(OH) 2 . 45,48 And similar reasons can also be found in IrO 2 where the synergistic effect between Ni and Ir and the interface effect between IrO 2 /Ir are both absent.…”