Effect of plasma pretreatment of Co–Cu–B catalyst on hydrogen generation from sodium borohydride methanolysis

Superior hydrogen production during sodium borohydride methanolysis using monodisperse copper nanoparticles grafted on the peptidoglycan layer of Bacillus atrophaeus bacteria

Recently, "Bacillus atrophaeus", which has a cell wall structure consisting of peptidoglycan layers, has attracted the attention of researchers due to its different usage areas. In particular, research focuses on the technology of obtaining bio‑hydrogen with various techniques. This research involves, for the first time, the use of the Bacillus atrophaeus bacteria as a bio-supporting material for monodisperse copper nanoparticles (CuNPs@Bacillus atrophaeus) and the manufacture of hydrogen through catalytic NaBH4-methanolysis (SB-methanolysis) in the presence of the resulting nanoparticles. Here, detailed kinetic studies were carried out during the SB-methanolysis by taking CuNPs and bacteria in varying amounts and at varying temperatures, and the activation energy and lifetime of monodisperse CuNPs@Bacillus atrophaeus was found to be 31.76 kJ mol-1 and 30,903 mol H2 (mol Cu)-1, respectively. The chemical and physical structure of the CuNPs@Bacillus atrophaeus was observed during the SB-methanolysis, so only detailed characterization of bacteria and monodisperse CuNPs@Bacillus atrophaeus was performed, and the particle size of the catalyst was calculated as 3.29 nm. The results showed that the monodisperse CuNPs@Bacillus atrophaeus, which has superior features and high catalytic activity, is a "clean", very well methanol-soluble, and quite surprising catalyst in terms of hydrogen production.

Catalytic hydrolysis of sodium borohydride for hydrogen production using phosphorylated silica particles

Hydrolysis of sodium borohydride (NaBH₄) offers substantial applications in the production of hydrogen but requires an inexpensive catalyst. Herein, silica (SP) and phosphorylated silica (SP-PA) are used as a catalyst for the generation of hydrogen from NaBH₄ hydrolysis. The catalyst is prepared by sol-gel route synthesis by taking tetraethyl orthosilicate as the precursor of silica whereas phosphoric acid served as the gelation and phosphorylating agent. The prepared catalyst is characterized by FT-IR spectroscopy, XRD, SEM, and EDAX. The hydrogen generation rate at SP-PA particles (762.4 mL min^-1 g^-1) is higher than that of silica particles (133 mL min^-1 g^-1 of catalyst). The higher catalytic activity of SP-PA particles might be due to the acidic functionalities that enhance the hydrogen production rate. The kinetic parameters (activation energy and pre-exponential factor) are calculated from the Arrhenius plot and the thermodynamic parameters (enthalpy, entropy, and free energy change) are evaluated using the Erying plot. The calculated activation energy for NaBH₄ hydrolysis at SP-PA catalyst is 29.92 kJ.mol^-1 suggesting the high catalytic activity of SP-PA particles. The obtained entropy of activation (ΔS‡ =  - 97.75 JK^-1) suggested the Langmuir-Hinshelwood type associative mechanism for the hydrolysis of NaBH₄ at SP-PA particles.