Unravelling the Alloy Effect of Porous Binary Pd-Based Nanostructures on Electrocatalytic Oxidation of Carbon Monoxide in Different Electrolytes

Abstract

Binary Pd-based nanostructures are highly efficient electrocatalysts for various applications. However, the alloy effect and electrolyte pH on CO oxidation (COoxid) remain ambiguous. This work presents a facile fabrication of porous PdM (M = Cu, Au, and Mn) spongy-like nanostructures via an aqueous-phase chemical reduction method for the electrocatalytic COoxid. The fabrication process comprises the direct ice-chemical reduction of binary metal precursors by sodium borohydride (NaBH4), without the need for supports, organic solvents, surfactants, and heating, but driven by the burst nucleation and coalescence growth mechanism. The COOxid activities and stabilities of PdM nanostructures were superior to commercial Pd/C catalysts in acidic, alkaline, and neutral electrolytes, due to the porous morphology, alloy effect, clean surface, and absence of the support, but PdCu has the highest COOxid activity. Mainly, the COOxid activity of PdCu nanocrystals was higher than those PdMn, AuPd, and Pd/C catalysts by at least 1.74, 1.14, and 2.63-folds in H2SO4, KOH, and NaHCO3, respectively, in addition to their excellent durability for 1000 cycles. This implies that PdCu alloy with a higher strain is preferred for promoting the COOxid, due to the greater electron/mass transport, higher active surface area, and greater oxophilicity of Cu-enabled fast H2O activation/dissociation at a lower potential. This study may allow formation of other self-standing Pd-alloys for electrocatalytic COOxid.

Assessing the Intrinsic Activity of Pt‐Group Electrocatalysts for Carbon Monoxide Oxidation: Best Practices and Benchmarking Parameters

“…Modulation the d-band center of Pd with Co, Cu, Ni, Fe, Au, and Mn without support enhanced the performance significantly than Pd/C catalysts in different electrolytes, but it was better in KOH. [93,95] PdFe with a higher strain effect was superior to all other alloys. [95] Porous Pt nanodendrites and Pd nanocubes are the most promising in different electrolytes,due to higher ECSA and maximized atom utilization.…”

“…The I CO of porous PdCu nanosponge was more than 1.74, 1.14, and 2.63 times higher than those of PdMn, AuPd, and Pd/ C nanosponges in H 2 SO 4 , KOH, and NaHCO 3 , respectively, besides of great stability for 1000 cycles. [93] Also, the EIS data demonstrated the lower charge transfer resistance and better electrolyte interaction of PdCu, PdMn, AuPd, and Pd/C than Pd/ C, as shown in the lower R s , R ct , and higher CPE. Notably, PdCu nanosponge [83] outperformed previously reported PtPd nanodendrites in KOH, [85] PtPd nanodendrites in H 2 SO 4 , [90] and AuPd/ C in H 2 SO 4.…”

“…To check the effect of composition, we fabricated bimetallic porous 3D porous PdCu (3.21 nm), PdMn (7.33 nm), and AuPd (7.96 nm) nanosponge with clean surfaces (i. e., no capping agent or surfactant) and average pore diameter (2-10 nm) by the aqueous-phase ice-reduction method in presence of NaBH 4 method. [93] The electrocatalytic CO oxid performance of Pd alloys was superior to commercial Pd/C catalysts in H 2 SO 4 , KOH, and NaHCO 3 , but PdCu had the utmost CO Oxid activity in all electrolytes. The I CO of porous PdCu nanosponge was more than 1.74, 1.14, and 2.63 times higher than those of PdMn, AuPd, and Pd/ C nanosponges in H 2 SO 4 , KOH, and NaHCO 3 , respectively, besides of great stability for 1000 cycles.…”

Controlling the Synthesis Protocols of Palladium‐Based Nanostructures for Enhanced Electrocatalytic Oxidation of Carbon Monoxide: A Mini‐Review

“…[6][7][8] Also, Pd-based catalysts are endowed with impressive properties (i. e., great electrochemical active surface area, low density, quick charge mobility, and ease adsorption/diffusion of reactants) that benefit CO Oxid electrocatalysis. [11,12] To defeat the high-cost and earth-rarity of Pd metal, it is usually mixed with other low-cost and earth-abundant metals/metal oxides (i. e., Co, TiO 2 , SiO 2 , Ce 2 O 3 , Fe 2 O 3 , Ni, Fe, Cu). [13][14][15][16][17] This not only reduces the usage of Pd but also modulates the d-band center of Pd (i. e., upshifting or downshifting), resulting in accelerating the CO Oxid kinetics at low potential and facilitating desorption of intermediates/products.…”