Cu²⁺-Decorated Porous Co₃O₄ Nanosheets for Photothermocatalytic Oxidation of Toluene

Abstract

Surface decoration has been demonstrated as one of effective ways of improving the catalytic activities of nanostructured materials. Herein, we report quenching as an effective synthetic strategy for decorating porous Co3O4 nanosheets. The hot Co3O4 nanosheets are poured into an aqueous solution of copper nitrate to obtain a surface Cu-decorated Co3O4 catalyst (Cu-Co3O4-Q). Cu-Co3O4-Q exhibits significant photothermocatalytic activity for toluene oxidation under irradiation of the full solar spectrum with light of 834 mW cm–2 (space velocity of 72000 mL g–1 h–1). The reaction rate of Cu-Co3O4-Q is 1.76 times higher than that of Co3O4. Comprehensive characterizations demonstrate that the Cu decoration is confined to the limited surface layers of Co3O4, different from a traditional hydrothermal synthesis method (Cu-Co3O4-T). Cu2+ substitution for Co2+ is preferred over Co3+ on the surface of Cu-Co3O4-Q and thus produces more active sites, leading to a catalytic activity comparable to that of partially supported noble-metal catalysts. The present work demonstrates that quenching is a facile and useful strategy for the decoration of nanostructured materials with enhanced photothermocatalytic performance.

A Hydrothermally Stable Single-Atom Catalyst of Pt Supported on High-Entropy Oxide/Al2O3: Structural Optimization and Enhanced Catalytic Activity

“…Figure d shows the Co 2p XPS spectra. The peak at 779.1 eV was attributed to Co 3+ , while the characteristic peak at 781.2 eV was attributed to Co 2+ . − The Co 2+ /Co 3+ relative ratio in HEO/Al 2 O 3 (0.38) was higher than that in the HEO sample (0.22), indicating that more oxygen vacancies were generated, with the particle size of HEO decreasing to the nanoscale level, , further confirming the results of the above temperature-programmed analysis. Based on the above analysis, we demonstrated that the designed continuous interfaces effectively prevented the further growth of the HEO microparticles, while more oxygen vacancies were generated on HEO because of the nanoscale effect, which resulted in the high dispersion of Pt species on the surface of HEO (Pt–O–M bonds).…”

Activating Metal Oxides Nanocatalysts for Electrocatalytic Water Oxidation by Quenching-Induced Near-Surface Metal Atom Functionality

“…TEM and EDAX show a homogeneous distribution of Co, O and metal heteroatoms in the quenched products (Figure a and Figure S34). Raman spectroscopy shows that the main Co–O peak in the quenched Co 3 O 4 NRs is located at a higher Raman shift than that of Co 3 O 4 NRs-NC, indicating that quenching changes the surface electronic structure and Co–O coordination environment (Figure b). , XPS (Figure c and Figure S35) reveals that quenching causes more Co 3+ ions in the surface region of Co 3 O 4 NRs-Fe-1 to be reduced to Co 2+ , giving a higher Co 2+ /Co 3+ ratio (1.05) compared with Co 3 O 4 NRs-NC (0.76). The higher fraction of Co 2+ in Co 3 O 4 NRs-Fe-1 is consistent with the presence of more surface oxygen defects …”

Engineering Cobalt Oxide with Coexisting Cobalt Defects and Oxygen Vacancies for Enhanced Catalytic Oxidation of Toluene

“…Moreover, the peak intensity of F 2g symmetry at 187 cm −1 exhibits obvious reduction, indicating a smaller long-range order. 30,43 The decrease for both shortrange order and long-range order reveals the existence of abundant defect sites, especially in Co 3−x O 4−y . 39,44 To further explore the composition of surface oxygen species and the charge distribution, XPS was carried out.…”