Dual‐Template Pore Engineering of Whey Powder‐Derived Carbon as an Efficient Oxygen Reduction Reaction Electrocatalyst for Primary Zinc‐Air Battery

Abstract

Cost-effective and high-performance electrocatalysts for oxygen reduction reactions (ORR) are needed for many energy storage and conversion devices. Here, we demonstrate that whey powder, a major by-product in the dairy industry, can be used as a sustainable precursor to produce heteroatom doped carbon electrocatalysts for ORR. Rich N and S compounds in whey powders can generate abundant catalytic active sites. However, these sites are not easily accessible by reactants of ORR. A dual-template method was used to create a hierarchically and interconnected porous structure with micropores created by ZnCl 2 and large mesopores generated by fumed SiO 2 particles. At the optimum mass ratio of whey power: ZnCl 2 : SiO 2 at 1 : 3 : 0.8, the resulting carbon material has a large specific surface area close to 2000 m 2 g À 1 , containing 4.6 at.% of N with 39.7% as pyridinic N. This carbon material shows superior electrocatalytic activity for ORR, with an electron transfer number of 3.88 and a large kinetic limiting current density of 45.40 mA cm À 2. They were employed as ORR catalysts to assemble primary zinc-air batteries, which deliver a power density of 84.1 mW cm À 2 and a specific capacity of 779.5 mAh g À 1 , outperforming batteries constructed using a commercial Pt/C catalyst. Our findings open new opportunities to use an abundant biomaterial, whey powder, to create high-value-added carbon electrocatalysts for emerging energy applications.

Confined Synthesis of N, P Co–Doped 3D Hierarchical Carbons as High‐Efficiency Oxygen Reduction Reaction Catalysts for Zn–Air Battery

“…al developed a dual-template method to prepare hierarchically and interconnected porous carbon for ORR. [25] However, most of the reported methods nowadays including the synthesis of regular SiO 2 nanoparticles or spheres, polymerization of carbon source on SiO 2 and removing SiO 2 template under harsh HF or NaOH solutions, which brings tedious steps for the synthesis of carbon catalysts and limits the advantages of SiO 2 template. [26][27] Therefore, it is very attractive to develop more facile and convenient method to synthesis carbons based on SiO 2 template.…”