Heteroatom-Doped Hierarchically Porous Biochar for Supercapacitor Application and Phenol Pollutant Remediation

Abstract

Biochars are considered as promising materials in energy storage and environmental remediation because of their unique physicochemical properties and low cost. However, the fabrication of multifunctional biochar materials with a well-developed hierarchical porous structure as well as self-doped functionalities via a facile strategy remains a challenge. Herein, we demonstrate a heteroatom-doped porous biochar, prepared by a hydrothermal pretreatment followed by a molten salt activation route. With the creation of a high specific surface area (1501.9 m2/g), a hierarchical porous structure, and the incorporation of oxygen-/nitrogen-functional groups, the as-prepared biochar (BC-24) exhibits great potential for supercapacitor application and organic pollutant elimination. The assembled biochar electrode delivers a specific capacitance of 378 F/g at 0.2 A/g with a good rate capability of 198 F/g at 10 A/g, and excellent cycling stability with 94.5% capacitance retention after 10,000 recycles. Moreover, BC-24 also exhibits superior catalytic activity for phenol degradation through peroxydisulfate (PDS) activation. The phenol (0.2 mM) can be effectively absorbed and then completely degraded within only 25 min over a wide pH range with low catalyst and PDS dosages. More importantly, TOC analysis indicates 81.7% of the phenol is mineralized within 60 min, confirming the effectiveness of the BC-24/PDS system. Quenching experiments and EPR measurements reveal that SO4·− and ·OH as well as 1O2 are involved in the phenol degradation, while the non-radical pathway plays the dominant role. This study provides valuable insights into the preparation of cost-effective carbon materials for supercapacitor application and organic contaminant remediation.

Hollow nanocages of vanadium nitride-based electrode material designed for superior charging/discharging stability supercapacitors

“…1 In particular, people's excessive exploitation of oil and the logging of trees have brought a huge burden to the environment. The resulting greenhouse effect, 2 the pollution of water resources, 3 the indiscriminate emission of toxic gases, 4 and even the biological pollution 5 caused by chemical pollutants 6 seriously threaten people's daily lives. There is an urgent need to develop new energy sources or find alternative energy to solve these imminent problems.…”

Effect of Surface Modification by Oxygen-Enriched Chemicals on the Surface Properties of Pine Bark Biochars

“…Biochar's source material is often discarded biomas, and as it is formed, itlocks in residual carbon from this biomass into its porous solid structure, and thus prevents that the carbon from returning to the atmosphere in the form of carbon dioxide [5]. Moreover, biochar can be utilized in different environmental applications such as wastewater treatment [6,7], energy storage [8,9], biofuel Processes 2022, 10, 2136 2 of 12 production [10,11], gas scrubbing [12,13], soil amendments [14,15], cattle feed [16,17], catalytic degradation of pollutants [18,19], and making cementitious materials [20,21]. Biochar's potential as a carbon-negative technology made from waste which simultaneously contributes economic benefits makes it pertinent to achieving sustainable development goals.…”

“…Oxygen functional groups have also been reported to be effective in the photodegradation of antibiotic drugs, such as, enrofloxacin [25]. Oxygen functional groups also enhanced supercapacitor activity in water hyacinth hydrochar [8]. Thus, intentional oxygen modification of biochar has been studied with a number of oxidizing agents, such as potassium hydroxide, nitric acid, sulfuric acid, potassium permanganate, air, and ozone [24,26].…”