Activity Origins and Design Principles of Nickel-Based Catalysts for Nucleophile Electrooxidation

Hollow NiSe Nanocrystals Heterogenized with Carbon Nanotubes for Efficient Electrocatalytic Methanol Upgrading to Boost Hydrogen Co‐Production

“…[ 5,12,25,29 ] In previous studies for Ni‐based anodic electrocatalysts, the higher oxidation state of transition metal (e.g., Ni 3+ ) as well as the NiOOH species are considered as critical active sites for electro‐oxidation reaction (e.g., OER). [ 28,29,57 ] Nevertheless, the MUR on h‐NiSe/CNTs/CC is preferable at lower potential than full water electrolysis. Besides, the catalytic current obtained at the potential greater than 1.47 V (vs RHE) is accompanied by observable O 2 production for OER.…”

“…Compared with the fresh h‐NiSe/CNTs‐f in Figure a, the h‐NiSe/CNTs‐s shows an obvious decrease of the XPS peak at ≈853 eV belonging to metallic Ni. [ 5,10,14 ] The h‐NiSe/CNTs‐o exhibits new emerged XPS peaks (Figure 3a) at 857.2 and 875.0 eV, respectively for Ni 2p 3/2 and Ni 2p 1/2 , suggesting the partial formation of higher valent Ni 3+ after 20 hours’ methanol conversion, [ 29,49,57 ] accompanied with the disappearance of the peak for metallic Ni. The phenomenon of gradual hydroxylation/oxidation is also demonstrated by the appearance of O 2− species (lattice oxygen, Figure 3b) at 530.1 eV in h‐NiSe/CNTs‐s and highly increased intensity of O 2− peak in h‐NiSe/CNTs‐o.…”

“…The absorption edges of h‐NiSe/CNTs‐f, h‐NiSe/CNTs‐s, and h‐NiSe/CNTs‐o shift to the high energy and their corresponding white lines shift to the low energy step by step, which clearly indicates that the valence state of Ni atom in h‐NiSe/CNTs is gradually increased during methanol selective oxidation. [ 57,59–61 ] Besides, the white‐line of h‐NiSe/CNTs‐o is obviously intensified compared with the h‐NiSe/CNTs‐f, suggesting that the higher oxidation state of Ni is formed by further hybridization between more Ni 4 p orbitals with Ni 3 d orbitals. [ 59,61–63 ] Figure 4b presents the Fourier transform curves of the extended XAFS (FT‐EXAFS) in R space that indicate the radial distribution function of Ni atoms.…”

“…In OER studies with Ni contained electrocatalysts, two Raman peaks at 476 and 555 cm −1 are regarded as the NiO vibrations of NiOOH. [ 57,66 ] These two peaks start to appear at 1.42 V (vs RHE), and they are gradually intensified with the increase of working potentials. The Raman peaks for NiOOH still appear after the stop of I‐t until a new electrochemical procedure is conducted at the reductive potential of −0.08 V (vs RHE), indicating that the formation of NiOOH is a critical step in the activation pathway of OER.…”

Tuning the Selective Adsorption Site of Biomass on Co3O4 by Ir Single Atoms for Electrosynthesis

“…Alternatively, replacing the sluggish OER with biomass oxidation reactions could significantly reduce the cell voltage and simultaneously achieve high‐value chemicals. [ 3 ] 5‐Hydroxymethylfurfural (HMF), as one of the vital biomass chemicals, can be selectively oxidized into pharmaceuticals, agrochemicals, and monomers. [ 4 ] 2,5‐furandicarboxylic acid (FDCA), derived from HMF, is an important monomer for the production of poly(ethylene 2,5‐furandicarboxylate) for the replacement of petroleum‐derived polyethylene terephthalate.…”