Microwave-assisted hydrothermal synthesis of Cu/Cu₂O hollow spheres with enhanced photocatalytic and gas sensing activities at room temperature

Abstract

Cu/Cu2O nano-heterostructure hollow spheres with a submicron diameter (200-500 nm) were prepared by a microwave-assisted hydrothermal method using Cu(OAc)2·H2O, PVP and ascorbic acid solution as the precursors. The morphology of the products could evolve with the hydrothermal time from solid spheres to thick-shell hollow spheres, then to thin-shell hollow spheres, and finally to nanoparticles. Moreover, the content of Cu in the products could be controlled by adjusting the hydrothermal time. The spontaneous forming of the hollow structure spheres was found to result from the Ostwald ripening effect during the low temperature (100 °C) hydrothermal reaction process. The photocatalytic degradation activities on MO under visible-light irradiation and the gas sensing activities toward the oxidizing NO2 gas of different Cu/Cu2O nano-heterostructure hollow spheres were investigated. As a result, the Cu/Cu2O nano-heterostructure hollow spheres obtained at the hydrothermal time of 30 min, with a rough/porous thin-shell structure and a Cu content of about 10.5 wt%, exhibited the best photocatalytic and gas sensing performances compared with others.

Facile Synthesis of Cu/Cu2O Nanoparticles–Graphene Composites for Efficient Detection of NO2 at Room Temperature

“…When exposed to 5 ppm NO 2 , a decrease in resistance of the CuGC2 has been observed and the response was about 3%, indicating that high gas response can be achieved in detecting low concentration NO 2 using CuGC2 as a sensing material. 10 Cu nanoparticles have relatively high work function (Cu: 4.65 eV; graphene: 4.6 eV) in the Cu/rGO heterostructure, which means that Cu nanoparticles are good electron acceptors in the CuGCs and the electrons transfer from graphene to Cu. When the sensor¯lm is exposed to NO 2 , the gas molecules could attract the electrons from Cu that existed in architectures.…”

“…Also we can¯nd that the relative intensity of Cu peaks decreases as the introduction of GO, indicating the lower content of Cu in the products. According to the previous study, 10 the mass fraction of Cu 2 O in Cu/Cu 2 O can be calculated using the relative ratio: I Cu2Oð111Þ /[I Cu2Oð111Þ þ I Cuð111Þ ], where I Cu2Oð111Þ and I Cuð111Þ are the intensities of the characteristic di®raction peaks of Cu 2 O (111) and Cu (111) planes, respectively. The calculated results are shown in Table S1.…”

“…Some techniques have been developed to enhance the sensing performance, including morphological control, 7-9 heterostructure formation and metal nanoparticles modifying. [10][11][12][13][14] Yang et al found that Cu/Cu x O nanoarchitectures showed e®ective detection to NO x . 10 At the same time, Sonawane et al studied the e®ects of Cu doping on good gas sensing properties.…”

“…[10][11][12][13][14] Yang et al found that Cu/Cu x O nanoarchitectures showed e®ective detection to NO x . 10 At the same time, Sonawane et al studied the e®ects of Cu doping on good gas sensing properties. 15 Graphene, a two-dimensional (2D) sheet of sp 2 -hybridized carbon atoms have received much attention due to its good electronic conductivity, large speci¯c surface area and high electronic mobility.…”

One‐Pot Synthesis of Cu2O Octahedron Particles and Their Catalytic Application

“…[8][9][10][11][12][13] To date, little reports have been reported for the reduction catalysts based on Cu 2 O nanostructures. Cu 2 O exhibited excellent performance as a catalyst for pollution remediation and photo-activated water splitting under visible light.…”