Porous Ni–Cu Alloy Dendrite Anode Catalysts with High Activity and Selectivity for Direct Borohydride Fuel Cells

Abstract

A porous Ni–Cu alloy dendrite catalyst covered by Ni nanoparticles (Ni-np@NC) has been fabricated by an ultrafast and controllable strategy. The research results show that the morphology of the Ni–Cu alloy depends strongly on the Cu2+concentration. Moreover, the Ni-np@NC catalyst demonstrates excellent selectivity and activity toward the borohydride oxidation reaction (BOR). Furthermore, on the Ni-np@NC catalyst electrode, the overpotential merely requires 169 mV at a current density of 10 mA cm–2 for BOR, and the fuel efficiency may reach 70%. The direct borohydride fuel cell using the Ni-np@NC/C anode can export a maximum power density of 218 mW cm–2, much higher than that using the noble-based anode reported in the literature. The remarkable enhancement of Ni-np@NC catalyst performances is on the back of the unique morphology of porous dendrite covered by nanoparticles and the introduction of Cu.

Succulent-plant-like Ni–Co alloy efficient catalysts for direct borohydride fuel cells

“…A direct borohydride fuel cell (DBFC) uses borohydride alkaline solution as the fuel and oxygen or hydrogen peroxide as the oxidant. When O 2 is used as the oxidant, the following reactions are involved during DBFC operation: [1][2][3][4][5]…”

“…A direct borohydride fuel cell (DBFC) uses borohydride alkaline solution as the fuel and oxygen or hydrogen peroxide as the oxidant. When O 2 is used as the oxidant, the following reactions are involved during DBFC operation: 1–5 BH 4 − + 8OH − → BO 2 − + 6H 2 O + 8e − E θ = −1.24 V vs. SHE2O 2 + 4H 2 O + 8e − → 8OH − E θ = 0.40 V vs. SHEBH 4 − + 2O 2 → BO 2 − + 2H 2 O E θ = 1.64 V vs. SHE…”

“…Theoretically, the BOR is an 8-electron reaction, but in fact this is difficult to achieve due to the occurrence of inevitable borohydride hydrolysis as shown in eqn (4). Therefore, the total actual reaction equation of the BOR is expressed using eqn (5):…”

“…Nowadays, research studies on nickel-based catalysts of the DBFC have focused on (i) modification of metallic nickel, [29][30][31] (ii) alloys of nickel and noble metals, 1,[32][33][34][35][36] and (iii) alloys of nickel and non-precious or non-metallic metals. 2,4,5,[37][38][39][40] However, there are few research studies concerning simultaneously the activity, stability and selectivity of catalysts.…”

Ni-doped hyperbranched PdCu nanocrystals for efficient electrocatalytic borohydride oxidation

“…Among them, Cu and Ni are widely deployed as promising materials for various electrochemical reactions in alkaline media due to their high availability, low cost, and good resistance to corrosion. 15,22,32 In addition, regulating the electrocatalyst nanostructure is an effectual route for the preparation of high activity catalysts. [33][34][35][36][37] Among different nanostructures, the branched materials with interconnected nanoarchitectonics have generated growing interest because of the rapid charge diffusion, abundant active sites and high material stability; [38][39][40][41][42] however, the construction of highly branched metallic alloys is still a formidable challenge.…”