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In situ redox deposition of palladium nanoparticles on oxygen-deficient tungsten oxide as efficient hydrogenation catalysts

Xue, Na, Yu, Rui-Jin, Yuan, Cheng-Zong, Xie, Xiao, Jiang, Yi-Fan, Zhou, Hong-Yan, Cheang, Tuck-Yun, Xu, An-Wu
RSC advances 2017 v.7 no.4 pp. 2351-2357
adsorption, aqueous solutions, catalysts, catalytic activity, dissociation, electron transfer, electrons, hydrogen, hydrogenation, nanocomposites, nanoparticles, nanowires, oxygen, p-nitrophenol, palladium, styrene, tungsten oxide
Noble metal/metal oxide support hybrid materials have attracted tremendous interest due to their wide applications in catalysis. Herein, we have developed a novel and surfactant-free method to prepare Pd/WO₃₋ₓ composite materials with clean surfaces. Oxygen-vacancy-rich WO₃₋ₓ nanowires (NWs) provide free electrons to reduce Pd²⁺, and surface-clean Pd nanoparticles (NPs) directly grow on WO₃₋ₓ surfaces through an in situ redox reaction between reductive WO₃₋ₓ and metal salt precursor (Na₂PdCl₄) in aqueous solution. The as-obtained Pd/WO₃₋ₓ nanocomposites show excellent catalytic activities for the hydrogenation of 4-nitrophenol (4-NP) and styrene. The apparent rate constant for 4-NP reduction is 0.045 s⁻¹, over the Pd/WO₃₋ₓ catalyst. The turnover frequency (TOF) value for styrene hydrogenation is 1074.5 h⁻¹, thus, exhibiting high catalytic performance. Moreover, the obtained Pd/WO₃₋ₓ catalyst exhibits good stability. Oxygen vacancies in WO₃₋ₓ NWs can accelerate electron transport and promote hydrogen adsorption and dissociation on the surface of the catalyst. The strong interaction between Pd NPs and WO₃₋ₓ support contributes to the excellent performance. Our work provides a novel and simple strategy to directly fabricate other-noble metal NP loaded oxygen-deficient metal oxides as highly efficient catalysts for chemical transformation.