Plasma–Microreactor Integration for Green and Continuous Synthesis of Pt/GO Electrocatalysts

Abstract The green and continuous preparation of supported noble metal catalysts is crucial for both fundamental research and industrial applications but remains highly challenging. Herein, a continuous microflow strategy that integrates dielectric barrier discharge (DBD) plasma with microreactor technology is developed for the synthesis of Pt/graphene oxide (Pt/GO) electrocatalysts under ambient temperature and pressure. This method uses the synergistic effects of both techniques to achieve rapid in situ reduction and deposition of Pt nanoparticles (PtNPs) onto GO nanosheets, avoiding the use of toxic chemical reductants or high-temperature annealing. The resulting Pt/GO composites feature well-dispersed, crystalline PtNPs with small particle sizes and tunable Pt loadings (0–15 wt %), while the oxygen-containing functional groups on GO are well preserved during plasma treatment. The residence time of the reagents is estimated to be 26.4 s, with a mean particle size of 5.01 nm for the 15 wt % Pt/GO catalyst. The resulting Pt/GO composites exhibit apparent electrocatalytic performance toward both the hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR) in acidic and alkaline media. Specifically, in 1 M KOH electrolyte, the 15 wt % Pt/GO catalyst delivers a low overpotential of 60 mV at −10 mA·cm–2 and a Tafel slope of 66.37 mV·dec–1 for HER. For MOR, this catalyst achieves a high peak current density of 346.85 mA·cm–2 in alkaline solution, along with reduced charge-transfer resistance. Compared to the batch plasma-prepared sample and commercial 20 wt % Pt/C, our plasma-microreactor-synthesized 15 wt % Pt/GO catalyst shows competitive HER activity under the present testing conditions, better MOR performance, and enhanced durability in both acidic and alkaline environments. This work demonstrates the feasibility of plasma–microreactor integration as a green, continuous, and intensified route for the synthesis of high-performance supported noble metal catalysts.