Copper Nanoparticles on Graphene Support: An Efficient Photocatalyst for Coupling of Nitroaromatics in Visible Light

Abstract

Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm(-2) ) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.

Photocatalysis: Basic Principles, Diverse Forms of Implementations and Emerging Scientific Opportunities

“…[136] Interested readers are suggested to read several recent reviews on this topic. [137] We list this category here because many of these plasmonic materials are also known co-catalysts, such as metals including Au, [138] Ag, [139] Pd, [140] Cu, [141] Al, [142] and non-metals including Cu 2−x Se, [143] Cu 2−x S, [144] WO 3−x [145] and each of them features unique resonant photon wavelengths. Importantly, the resonant photon wavelength of the plasmonic nanoparticles can be tuned by varying their sizes, shapes, and material compositions.…”

Visible light-induced selective photocatalytic aerobic oxidation of amines into imines on Cu/graphene

“…[11] Blechert et al developed a metal-free, heterogeneous catalysis protocol for the oxidation using carbon nitride and visible light. [7,18,19] Studies on light-driven reactions catalyzed by Au or Ag nanoparticles have formed the basis of a new and fastexpanding field in green photocatalysis. [13] Localized surface plasmon resonance (LSPR) is the resonant photon-induced coherent oscillation of charge at the metaldielectric interface, established when the photon frequency matches the natural frequency of metal surface electrons oscillating against the restoring force of their positive nuclei.…”

“…[19] Because Cu based catalysts can thermally catalyze many organic reactions and they are more easily and abundantly available, herein we employ graphene supported Cu nanoparticles as the photocatalyst for aerobic oxidation of amines under visible light irradiation, and report its excellent photocatalytic performance. [19] Because Cu based catalysts can thermally catalyze many organic reactions and they are more easily and abundantly available, herein we employ graphene supported Cu nanoparticles as the photocatalyst for aerobic oxidation of amines under visible light irradiation, and report its excellent photocatalytic performance.…”

Bimetallic Oxide Nanoflowers Decorated Graphene Oxide Nanosheets as Novel Nanohybrids for 4-Nitrophenol Removal at Room Temperature

“…10−12 One of the critical steps in the design of GO-based advanced hybrid materials is the functionalization/decoration of GO with nanoparticles of metals or metal oxides. 13 This can improve the materials' intrinsic response by the control of homogeneity in size, morphology and dispersion of the metal or metal oxide components decorated on the basal GO. 14 Cobalt oxide being a highly researched component of spinel crystal group has potential as the catalyst for electrochemical/photochemical oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and gas sensing behavior, not only in pure but in hybrid form as well.…”