Regular arrangement of Pt nanoparticles on S-layer proteins isolated from Lactobacillus kefiri: synthesis and catalytic application

In this work, platinum bionanocatalysts using S-layer proteins isolated from two strains of Lactobacillus kefiri as template were obtained. TEM and STEM images evidenced that Pt/CBS8348 shows a P6-array while Pt/CBS83111 does not show any defined array. Noteworthy, nanometric and subnanometric Pt clusters were observed in both Pt/CBS8348 and Pt/CBS83111 catalysts, with an average metal particle size estimated by TEM of 3.62 and 3.88 nm, respectively. Also, Pt/CBS8348 showed a higher number of dispersed Pt single atoms than Pt/CBS83111. Both Pt bionanocatalysts showed an excellent performance in the reduction of p-nitrophenol, reaching conversion values close to 65-70% in 15 min. Besides, both Pt/CBS8348 and Pt/CBS83111 were successfully reused nine times, maintaining conversion values between 75 and 90%.