Efficient regulation of surface hydroxyl groups on a Pt/Na/AC catalyst using two-step nonthermal plasma for high formaldehyde oxidation performance

A novel catalyst was fabricated using a two-step nonthermal plasma method by regulating surface hydroxyl groups on Na/activated carbon (AC) with 0.1 wt% Pt loading (Pt/Na/AC (P&P)) and achieved high formaldehyde (HCHO) oxidation performance at ambient temperature. Based on characterization results, we found that in the first step of nonthermal plasma treatment under argon-water, the proportion of terminal OH groups (ter-OH groups) evidently increased. Following the introduction of Na and Pt, the relative abundance of doubly bridged OH groups connecting C and Na (bri_Na-C-OH groups) and Pt²⁺ species also increased in the second step of nonthermal plasma reduction under argon, resulting in enhanced HCHO catalytic oxidation capability through a rapid reaction pathway ([HCOO^-] + [OH]_a → CO₂ + H₂O). Compared with the catalyst prepared via nitric acid oxidation and thermal deposition (Pt/Na/AC (H&T)), more Pt-O_x-Na species and surface OH groups were obtained on the Pt/Na/AC (P&P) catalyst, which not only reduced Pt consumption but also improved HCHO catalytic activity with around 100% conversion of HCHO to CO₂ at 25 °C, while the Pt/Na/AC (H&T) catalyst only achieved 70% conversion. This work thus provides a new strategy for HCHO oxidation at room temperature and a novel perspective on the environmentally friendly synthesis of effective noble catalysts.