Hydrothermally Carbonized Waste Biomass as Electrocatalyst Support for α-MnO2 in Oxygen Reduction Reaction

Harold O Panganoron,Jethro Daniel A Pascasio,Eugene A Esparcia,Julie Anne D Del Rosario,Joey D Ocon

doi:10.3390/catal10020177

Harold O Panganoron, Jethro Daniel A Pascasio + Show 3 more

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https://doi.org/10.3390/catal10020177

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Abstract

Sluggish kinetics in oxygen reduction reaction (ORR) requires low-cost and highly durable electrocatalysts ideally produced from facile methods. In this work, we explored the conversion and utilization of waste biomass as potential carbon support for α-MnO2 catalyst in enhancing its ORR performance. Carbon supports were derived from different waste biomass via hydrothermal carbonization (HTC) at different temperature and duration, followed by KOH activation and subsequent heat treatment. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX) and X-Ray diffraction (XRD) were used for morphological, chemical, and structural characterization, which revealed porous and amorphous carbon supports for α-MnO2. Electrochemical studies on ORR activity suggest that carbon-supported α-MnO2 derived from HTC of corncobs at 250 °C for 12 h (CCAC + MnO2 250-12) gives the highest limiting current density and lowest overpotential among the synthesized carbon-supported catalysts. Moreover, CCAC + MnO2 250-12 facilitates ORR through a 4-e‑ pathway, and exhibits higher stability compared to VC + MnO2 (Vulcan XC-72) and 20% Pt/C. The synthesis conditions preserve oxygen functional groups and form porous structures in corncobs, which resulted in a highly stable catalyst. Thus, this work provides a new and cost-effective method of deriving carbon support from biomass that can enhance the activity of α-MnO2 towards ORR.

Highlights

The use of electrochemical energy technologies, such as batteries and fuel cells, are effective and practical ways of dealing with stability issues brought by intermittent renewable energy sources.At present, lithium-ion chemistries dominate among energy storage technologies and cover a wide array of applications
We investigate the derivation of carbon supports from different waste biomass materials including corncobs, coffee waste grounds, rice hulls, and coconut lumber sawdust
We successfully synthesized and evaluated carbon support for α-MnO2 through hydrothermal carbonization followed by KOH activation and heat treatment

Summary

Introduction

The use of electrochemical energy technologies, such as batteries and fuel cells, are effective and practical ways of dealing with stability issues brought by intermittent renewable energy sources. Lithium-ion chemistries dominate among energy storage technologies and cover a wide array of applications. Metal-air batteries (MABs) are seen to address the challenges for renewable energy applications and other niche applications [1,2]. The utilization of ambient air in energy storage applications is constrained by the sluggish kinetics of the oxygen reduction reaction (ORR) [3]. Previous studies have focused on the development of electrocatalysts to enhance ORR performance [4,5,6].

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