Biomass-based Hierarchical Porous ORR and OER Bifunctional Catalysts with Strong Stability for Zn-Air Batteries

Abstract

Although the Zn-air battery has many advantages, its short practical life hinders its development. Many solutions have been proposed and extensively studied. In this paper, a cobalt-nitrogen co-doped hierarchical porous carbon-based bifunctional catalyst (Co/N-HPCs-800) is reported, using sustainable and low-cost sodium alginate (Na-Alg), a common seaweed extract, as a precursor to complex excess metal particles. The hydrogel network formed by the exchange of sodium ions with metal cation (Co 2+ ) ions is the key to the controllable synthesis of highly dispersed metal atoms. Co/N-HPCs-800 shows excellent catalytic performance and durability in oxygen reduction reaction (E 1/2 = 0.86 V) and oxygen evolution reaction (367 mV @ 10 mA cm −2 ). Importantly, we only attenuated the half-wave potential by 8 mV after more than 50,000 cycles. In addition, the Zn-air batteries (ZABs) using Co/N-HPCs-800 as a cathode exhibit a power density up to 159.67 mW cm −2 and a high specific capacity of 787.94 mA h g −1 . This work opens up practical new strategies for synthesizing excess metal catalysts in low cost, effectively improving the service life of Zn-air batteries.

Self-Sacrificial Templated Nanoarchitectonics of Nitrogen-Doped Carbon Derived from Viologen-Based Covalent Triazine Polymer: An Oxygen Reduction Electrocatalyst in Zinc–Air Batteries

“…50,51 Third, from the BET studies, it is evident for the presence of a higher specific surface area in both ACTP-1 and ACTP-2, but the former lacks the active site necessary for the mass transport of the ORR catalytic activity which is not the case with the latter, leading to enhanced activity. 52 Finally, ACTP-2, though it showed slight tolerance toward the methanol crossover effect when compared to Pt/C, has high utility in zinc−air batteries.…”

“…Generally, nitrogen-doped carbon is regarded as a superior oxygen reduction catalyst as it creates sufficient tunable micro- and mesopores, and with enhanced nitrogen doping a high degree of graphitization is obtained . It has been claimed that pyridinic nitrogen offers π electrons to the aromatic system, which in turn boosts the ability to donate electrons and as an outcome of which the ORR activity is enhanced. , Third, from the BET studies, it is evident for the presence of a higher specific surface area in both ACTP-1 and ACTP-2, but the former lacks the active site necessary for the mass transport of the ORR catalytic activity which is not the case with the latter, leading to enhanced activity . Finally, ACTP-2, though it showed slight tolerance toward the methanol crossover effect when compared to Pt/C, has high utility in zinc–air batteries.…”

One-pot synthesis of biomass-derived porous carbons for multipurpose energy applications

“…, silk and seaweed) are an ideal candidate for preparing N-doped carbon-based electrocatalysts, which can be easily prepared without addition of chemical-N precursors. 221,222…”

Highly Active N, S Codoped Porous Carbon Derived from Lignin-Rich Pulping Waste Liquor for Supercapacitors and Oxygen Reduction Reaction

“…However, macroporous materials commonly possess low surface areas, which will undoubtedly reduce the number of exposed possible active sites. Thus, candidates with hierarchical porous carbons having a significant number of micropores in the outer surfaces of their mesopores and macropores are attractive because they can concurrently offer micropores for active site exposure and mesopores and macropores for effective mass transfer. − In general, the hierarchical porous carbons are prepared by using various nanotemplates, such as SiO 2, Al 2 O 3 , MgO, etc. However, the preparation of a uniform template with unique morphology, even distribution of the resulting templates in carbon-based precursors, chemical etching of the nanotemplates after carbonization, and the purification of the resulting carbons are some of the numerous difficult and time-consuming procedures involved in these traditional template-assisted methods.…”