Hierarchical PdNi alloy nanochains coupled with Ni(OH) nanosheets to enhance CO-poisoning resistance for the methanol oxidation reaction.

Hybridizing Pd-based electrocatalysts with Ni-based species has been recognized as an effective pathway to enhance the catalytic performance for the methanol oxidation reaction (MOR). However, doping Ni-based species with heterogeneous valences into Pd nanocrystals still remains challenging, although heterogeneous valence Ni species may result in improved properties of Pd from different aspects. Herein, a facile one-pot synthetic method is reported to simultaneously introduce alloyed Ni into Pd lattices and couple hydroxy Ni species with a Pd surface, generating 1D porous PdNi alloy nanochains@Ni(OH) nanosheet hybrids (PdNi NCs@Ni(OH) NSs). Borane--butylamine (CHBN) plays the key role in realizing the formation of Ni-based species with heterogeneous valence. On one hand, it works as a reducing agent to facilitate the doping of alloyed Ni into the lattice of Pd nanochains. On the other hand, it raises the solution pH value and converts the remaining [Ni(CN)] into Ni(OH) nanosheets. Each component of the PdNi NCs@Ni(OH) NSs plays an important role: Pd serves as the active site, alloyed Ni modifies the electronic structure of Pd, and Ni(OH) provides abundant OH species to strengthen the anti-poisoning capability, thus greatly enhancing the activity, CO-tolerance, and durability for the MOR.