Plasma synthesis of graphite oxide supported PdNi catalysts with enhanced catalytic activity and stability for 4-nitrophenol reduction

Catalytic removal of 4-nitrophenol (4-NP) in wastewater remains a significant challenge due to the poor activity and stability of the catalysts. Herein, low-cost graphite oxide (GO) supported Pd and Ni NPs (PdNi/GO) with enhanced catalytic activity and stability for 4-NP reduction were synthesized by a plasma method in the aqueous solution of Pd(NO3)(2), Ni(NO3)(2), and GO. The normalized rate constant k(nor) over the PdNi/GO with Pd/Ni=1.8:0.2 for 4-NP reduction was as high as 5480 min(-1)center dot g(-1)center dot L, which was comparable with that of Pd/GO, and it was about 50.7 times higher than that of Pd/rGO-H prepared by traditional thermal reduction method. Importantly, after six reaction cycles, it only decreased to 74.8% of the initial value, which was much higher than that of the Pd/GO catalyst (59.8%). The characterization results indicated that plasma synthesized Pd/GO catalyst can keep the oxygen-containing groups (OCGs) on the GO surface, generate abundant defects, and facilitate the adsorption of the 4-NP. Interestingly, the addition of Ni could keep these merits, and the formed PdNi alloyed structure may facilitate the electron transfer between PdNi NPs and GO, contribute to the strong adsorption of 4-NP and the rapid generation of active hydrogen. Consequently, the PdNi/GO catalyst exhibited outstanding catalytic activity and stability for 4-NP reduction. This work provided a fast, facile, environmentally friendly, and easy to scale up plasma method for synthesizing high performance Pd-based catalysts.

Automated summary

In this study, low-cost Pd and Ni nanoparticles supported on graphite oxide (GO) with enhanced activity and stability for 4-NP reduction were synthesized by a plasma method. The PdNi/GO catalyst exhibited high catalytic activity, comparable to Pd/GO, and significantly higher than Pd/rGO-H prepared by traditional thermal reduction. The addition of Ni facilitated electron transfer, adsorption of 4-NP, and rapid generation of active hydrogen, leading to the outstanding catalytic performance and stability of the PdNi/GO catalyst.