Hydrothermal Carbonization‐Derived Carbon from Waste Biomass as Renewable Pt Support for Fuel Cell Applications: Role of Carbon Activation

Abstract

Pt catalysts in proton exchange membrane fuel cells (PEMFCs) typically use carbon blacks such as Vulcan (Vulcan is a registered trademark of the company Cabot Corporation) based on fossil sources. Thus, an important research task is using sustainable supports in PEMFCs. Hydrothermal carbonization (HTC) converts biomasses into chars, which are possible substitutes for fossil‐based carbons. Herein, a Pt catalyst derived from HTC of coconut shells is developed for catalysis of O2 reduction in acidic media. Thermal activation enlarges the specific surface area by factor of 7 to 546 m2 g−1 and generates electrical conductivity making the material suitable for catalysis. Pt particles of 1.8 ± 0.5 nm are distributed well on the activated carbon. Cyclic and CO stripping voltammetry show an electrochemical surface area (ECSA) of 69 ± 21 m2 gPt−1, almost identical to that of the commercial catalyst using Vulcan (69 ± 6 m2 gPt−1). Although ECSAs are highly comparable, the activity for O2 reduction is lower compared with the commercial catalyst. HTC‐derived carbon has a lower degree of graphitization, less functional oxygen groups on its surface, and a lower electrical conductivity than Vulcan. This suggests different Pt–support interactions.

Impact of Highly Stable Catalyst Support Materials on Polymer Electrolyte Membrane Fuel Cell Performance

“…For example, it should have high surface area, chemical and thermal stability, mechanical strength, electrical conductivity, effective metal support interactions, and catalyst particles that can uniformly be dispersed on its surface . Highly stable carbon‐based and noncarbon or inorganic cathode catalyst supports for PEMFCs are proposed by different scientists, as shown in previous studies. Graphitized carbons are found to be promising catalyst support materials in terms of both stabilities and activities as compared to nongraphitized carbon supports .…”

“…Activated carbon composites, xerogel–nanofiber carbon composites, carbon nanofibers, silica‐coated carbon nanotubes, and nitrogen‐doped carbons have also shown stable behavior when used as noble metal supports for PEMFC applications. Very recently Pt supported on hydrothermal carbonization‐derived carbon from waste biomass showed improved oxygen reduction reaction (ORR) catalysts; however, the stability of that carbon is still unfavorable for PEMFC applications . A highly active and stable Pt alloy on a support of novel nitrogen/metal codoped graphene tubes as cathode catalyst was also reported; however, transformation to membrane electrode assembly (MEA) is still unidentified.…”

Enhanced Breaking of Lignin and Mesopore Formation in Zinc Chloride Assisted Hydrothermal Carbonization of Waste Biomasses

“…The obtained hydrochars from HTC have received increasing interest in various relevant fields of the chemical industry, such as for catalysis, water purification, energy storage and CO 2 sequestration [7,8]. However, due to their low degree of porosity and small internal surface areas of less than 10 m 2 /g [9], the hydrochars mainly serve as precursors instead of competitive substitutes to the energy expensive activated carbons received by pyrolysis at high temperatures [10][11][12][13].…”

Softwood Kraft Pulp-Derived Carbon-Supported PtNi Catalysts for the Electrooxidation of Ethanol

“…On the other hand, a low-cost biosynthesis method using yeast cells as the precursor was used to fabricate a nitrogen-and phosphorus-doped biocarbon, which was employed as an electrode material for the oxygen reduction reaction (ORR) (Gong et al, 2015). More recently, coconut shells were used for the synthesis of biocarbons by hydrothermal carbonization and then subjected to physical, chemical, or thermal activation (Schonvogel et al, 2019). The coconut shell-derived carbon powders were used as supports of platinum nanoparticles for the ORR process.…”