In Situ Synthesis of a Highly Active AuPd/NH2-P-CNT Catalyst Using Citric Acid to Enhance Hydrogen Evolution from Formic Acid

A novel citric acid-assisted in situ reduction method has been developed for the synthesis of bimetallic AuPd alloy nanoparticles supported on amine–phosphate-functionalized carbon nanotubes (AuPd/NH2-P-CNTs). In this strategy, formic acid acts not only as the reducing agent for reducing metal precursors, but also as the hydrogen source for the subsequent catalytic dehydrogenation. The introduction of citric acid significantly accelerates the reduction kinetics and promotes the uniform formation of ultrafine AuPd nanoparticles (∼1.8 nm). As a result, the optimized Au0.5Pd0.5/NH2-P-CNTs exhibit an extraordinary catalytic activity and 100% H2 selectivity during hydrogen generation from FA with sodium formate as an additive, affording a remarkable initial turnover frequency of 5663.94 mol H2 mol Pd−1 h−1 at 303 K. The experimental results reveal that the -NH2 and -P functional groups on the support are crucial for stabilizing and uniformly dispersing the alloy nanoparticles. Furthermore, the enhanced reaction rate can be attributed to the strong metal–support interaction established between AuPd nanoparticles and -NH2-P-CNT supports. This work provides a new perspective on the design of highly efficient Pd-based catalysts for hydrogen production from formic acid.