Facile and fast synthesis of a reduced graphene oxide/carbon nanotube/iron/silver hybrid and its enhanced performance in catalytic reduction of 4–nitrophenol

Abstract

A facile, eco-friendly approach is proposed for fast preparation of a partially reduced graphene oxide/carbon nanotube/iron/silver hybrid (rGO/CNT/Fe/Ag) under ambient conditions. The partial reduction and exfoliation of GO, the ultrafast growth of CNT on the rGO surface, and the formation of AgNPs occurred simultaneously within 10–30 s using a domestic microwave oven. The morphology and structure of the rGO/CNT/Fe/Ag hybrid are discussed in detail, and a possible formation mechanism is proposed. The obtained rGO/CNT/Fe/Ag hybrid exhibited high catalytic activity for reduction of 4–nitrophenol (4–NP) by NaBH4 with a kinetic rate constant of 14.66 × 10−3 s−1, a normalized rate constant of 1884.31 s−1 × g−1 and a turnover frequency of 33.6 h−1 due to the synergistic effect of all consisting components in the hybrid. With a high surface area, GO serves as a good substrate for immobilization of more AgNPs, whereas rGO/CNT with a high electrical conductivity promoted the electron transfer in the reduction of 4–NP. AgNPs were the catalytic active sites for the reduction of 4–NP, whereas the presence of FeNPs and Fe3C facilitate for recovering and recycling the catalyst easily. Moreover, the rGO/CNT/Fe/Ag hybrid maintained high catalytic activity and stability after five cycles and easy reusability by an external magnet.