Stabilisation of high-valent Cu³⁺ in a Keggin-type polyoxometalate

Abstract

A Cu3+-containing polyoxometalate is synthesized by using the Ag+-assisted peroxydisulfate oxidation method and the existence of Cu3+ is proven by characterization.

Efficient Electrocatalytic Oxidation of 5-Hydroxymethylfurfural Coupled with 4-Nitrophenol Hydrogenation in a Water System

“…XPS was then employed to further verify the electrogenerated CuOOH active species on the CF-Cu­(OH) 2 surface. Figure a shows the high-resolution XPS spectrum of Cu 2p, where the binding energies of Cu 2p3/2 and Cu 2p1/2 are located at 934.1 and 954.1 eV for the CF-Cu­(OH) 2 sample with a spin energy separation of 20.0 eV, in good agreement with the reported value of the Cu 2p state in Cu­(OH) 2 . , After electrochemical activation, both Cu 2p3/2 and Cu 2p1/2 peaks shift to a higher energy level accompanied by the broadened peaks, suggesting the existence of Cu 3+ on the surface of the activated CF-Cu­(OH) 2 (Figure b). − Meanwhile, the XPS spectrum of the O 1s region shows three fitted peaks at 529.2, 530.8, and 532.1 eV (Figure c), corresponding to O species in the lattice (O L ), oxygen vacancies (O V ), and chemisorbed or dissociated oxygen species from water molecules (O C ) . After electrochemical activation, the significant enhancement of lattice (O L ) at the binding energy of 529.2 eV (Figure d) further reveals the formation of CuOOH active species on the surface of CF-Cu­(OH) 2 .…”

A Keggin-type polyoxomolybdate-based crystalline material formed by hydrothermal transformation: photo/electro-catalytic properties and mechanism study

“…The peak below 400 nm was mainly attributed to the area assigned for O to Mo charge transfer of the Keggin-type structure. 54 The peak located at around 420 nm is assigned to ligand-localized π–π* transitions. In addition, the broad absorption peak around 660 nm represents the d–d transitions assigned to 2 E g → 2 T 2g based on a Cu 2+ central ion.…”

Building a Z-scheme heterojunction with Keggin-type heteropolymer modified two-dimensional g-C3N4 for significant photocatalytic performance

“…Recently, many studies have been devoted to the functionalization of polymetallic oxygenated compounds in synthetic and industrial applications. 27,28 The most studied polymetallic oxygen-containing material is heteropolymers. 29,30 Due to their discrete ionic structure and high proton fluidity, they have a good application prospect in photocatalysis.…”