Facile Synthesis and Environmental Applications of Noble Metal-Based Catalytic Membrane Reactors

Noble metal nanoparticle-loaded catalytic membrane reactors (CMRs) have emerged as a promising method for water decontamination. In this study, we proposed a convenient and green strategy to prepare gold nanoparticle (Au NPs)-loaded CMRs. First, the redox-active substrate membrane (CNT-MoS2) composed of carbon nanotube (CNT) and molybdenum disulfide (MoS2) was prepared by an impregnation method. Water-diluted Au(III) precursor (HAuCl4) was then spontaneously adsorbed on the CNT-MoS2 membrane only through filtration and reduced into Au(0) nanoparticles in situ, which involved a "adsorption-reduction" process between Au(III) and MoS2. The constructed CNT-MoS2@Au membrane demonstrated excellent catalytic activity and stability, where a complete 4-nitrophenol transformation can be obtained within a hydraulic residence time of <3.0 s. In addition, thanks to the electroactivity of CNT networks, the as-designed CMR could also be applied to the electrocatalytic reduction of bromate (>90%) at an applied voltage of -1 V. More importantly, by changing the precursors, one could further obtain the other noble metal-based CMR (e.g., CNT-MoS2@Pd) with superior (electro)catalytic activity. This study provided new insights for the rational design of high-performance CMRs toward various environmental applications.