Varshney Shalaka, Meyerstein Dan, Bar-Ziv Ronen, Zidki Tomer
Chemical Sciences Department, The Centre for Radical Reactions and Material Research, Ariel University, Kyriat Hamada 3, Ariel 40700, Israel.
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Molecules. 2023 Sep 8;28(18):6530. doi: 10.3390/molecules28186530.
Assessing competitive environmental catalytic reduction processes via NaBH is essential, as BH is both an energy carrier (as H) and a reducing agent. A comprehensive catalytic study of the competition between the borohydride hydrolysis reaction (BHR, releasing H) and 4-nitrophenol reduction via BH on M- and M/M' (alloy)-nanoparticle catalysts is reported. The results reveal an inverse correlation between the catalytic efficiency for BH hydrolysis and 4-nitrophenol reduction, indicating that catalysts performing well in one process exhibit lower activity in the other. Plausible catalytic mechanisms are discussed, focusing on the impact of reaction products such as 4-aminophenol and borate on the rate and yield of BH hydrolysis. The investigated catalysts were Ag, Au, Pt, and Ag/Pt-alloy nanoparticles synthesized without any added stabilizer. Notably, the observed rate constants for the 4-nitrophenol reduction on Ag, Ag-Pt (9:1), and Au are significantly higher than the corresponding rate constants for BH hydrolysis, suggesting that most reductions do not proceed through surface-adsorbed hydrogen atoms, as observed for Pt nanoparticles. This research emphasizes the conflicting nature of BH hydrolysis and reduction processes, provides insights for designing improved catalysts for competitive reactions, and sheds light on the catalyst properties required for each specific process.
通过硼氢化钠评估竞争性环境催化还原过程至关重要，因为硼氢化钠既是一种能量载体（作为氢）又是一种还原剂。本文报道了在M和M/M'（合金）纳米颗粒催化剂上，对硼氢化物水解反应（BHR，释放氢）和通过硼氢化钠还原4-硝基苯酚之间的竞争进行的全面催化研究。结果表明，硼氢化钠水解的催化效率与4-硝基苯酚还原的催化效率呈负相关，这表明在一个过程中表现良好的催化剂在另一个过程中活性较低。文中讨论了合理的催化机制，重点关注了反应产物如4-氨基苯酚和硼酸盐对硼氢化钠水解速率和产率的影响。所研究的催化剂是在没有添加任何稳定剂的情况下合成的银、金、铂和银/铂合金纳米颗粒。值得注意的是，在银、银-铂（9:1）和金上观察到的4-硝基苯酚还原反应速率常数明显高于相应的硼氢化钠水解反应速率常数，这表明大多数还原反应不像在铂纳米颗粒上观察到的那样通过表面吸附的氢原子进行。这项研究强调了硼氢化钠水解和还原过程的冲突性质，为设计用于竞争性反应的改进催化剂提供了见解，并揭示了每个特定过程所需的催化剂特性。
