Kraft Lignin Derived Molybdenum Carbide/Nitrogen-Doped Carbon Composite for Efficient Hydrogen Evolution Reaction
TL;DR: In this paper, a simple, unique, and eco-friendly fabrication method for composites of molybdenum carbide nanoparticles dispersed on nitrogen-doped carbon supports (Mo2C/NC) by annealing of MoCl5, kraft lignin, urea at 750 ℃ under N2 flow in one pot.
Abstract: This paper reports a simple, unique, and eco-friendly fabrication method for composites of molybdenum carbide nanoparticles dispersed on nitrogen-doped carbon supports (Mo2C/NC) by annealing of MoCl5, kraft lignin, urea at 750 ℃ under N2 flow in one pot. Kraft lignin, a by-product from the pulping industry, acted as carbon source for formation of Mo2C and carbon support and a cheap urea provided a nitrogen source for nitrogen-doping to carbon supports. The resultant Mo2C/NC catalysts exhibited high activity with small overpotential (131 mV at 10 mA cm-2) and excellent stability over 3000 potential cycles for hydrogen evolution reaction (HER) in alkaline media. Enhanced HER activity of Mo2C/NC catalyst was attributed to highly active Mo2C nanoparticles and nitrogen-doped carbon (N-doped carbon) providing large surface area and high electrical conductivity.
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TL;DR: Lignin, which consists of about 30% organic carbon, is considered as one of the most ample biopolymers in the world as discussed by the authors and is considered to be the pathway to a greener circular world.
Abstract: Lignin, which consists of about 30% organic carbon, is considered as one of the most ample biopolymers in the world. It is one of the pathways to a greener circular...
3 citations
TL;DR: In this paper , a new electrochemical sensor based on a [email protected]x-modified polyethylene terephthalate electrode spin coated with PEDOT was developed for simultaneous determination of catechol (CT) and hydroquinone (HQ).
2 citations
TL;DR: In this article , a composite of Mo2C nanoparticles dispersed onto a nitrogen and sulfur co-doped carbon scaffold (Mo2C/N,S-C) was prepared by a simple and environmentally friendly method of one-pot annealing of MoCl5, urea, and lignosulfonate under a N2 atmosphere at 700 °C.
Abstract: A composite of Mo2C nanoparticles dispersed onto a nitrogen and sulfur co-doped carbon scaffold (Mo2C/N,S-C) was prepared by a simple and environmentally friendly method of one-pot annealing of MoCl5, urea, and lignosulfonate under a N2 atmosphere at 700 °C. Lignosulfonate, a by-product of the sulfite pulping process, was employed as a feedstock to fabricate the S-doped carbon scaffold and carbide simultaneously, and urea acted as a nitrogen source for N-doping to carbon. The as-prepared Mo2C/N,S-C catalyst showed high performance for the hydrogen evolution reaction (HER), with a small overpotential of 105 mV at 10 mAcm−2, and good stability for 3000 cycles. The improved HER performance of the Mo2C/N,S-C originated from the interplay between the highly active Mo2C nanoparticles and the N,S co-doped carbon scaffold with its high electrical conductivity and large surface area. Furthermore, N,S co-doping to carbon improved the hydrophilicity of the catalyst surface, thus further enhancing the HER activity.
1 citations
TL;DR: In this paper , a composite Mo2C-MoC heterostructured electrocatalyst is directly grown on Ni foam (NF) via the simple one-step annealing of MoCl5, urea, and NF under a flow of N2 at various temperatures for use in the hydrogen evolution reaction (HER).
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TL;DR: Identifying and building a sustainable energy system are perhaps two of the most critical issues that today's society must address.
Abstract: Identifying and building a sustainable energy system are perhaps two of the most critical issues that today's society must address. Replacing our current energy carrier mix with a sustainable fuel is one of the key pieces in that system. Hydrogen as an energy carrier, primarily derived from water, can address issues of sustainability, environmental emissions, and energy security. Issues relating to hydrogen production pathways are addressed here. Future energy systems require money and energy to build. Given that the United States has a finite supply of both, hard decisions must be made about the path forward, and this path must be followed with a sustained and focused effort.
4,824 citations
TL;DR: Fossil fuels currently supply most of the world's energy needs, and however unacceptable their long-term consequences, the supplies are likely to remain adequate for the next few generations.
Abstract: Fossil fuels currently supply most of the world's energy needs, and however unacceptable their long-term consequences, the supplies are likely to remain adequate for the next few generations. Scientists and policy makers must make use of this period of grace to assess alternative sources of energy and determine what is scientifically possible, environmentally acceptable and technologically promising.
4,005 citations
TL;DR: Recent developments in genetic engineering, enhanced extraction methods, and a deeper understanding of the structure of lignin are yielding promising opportunities for efficient conversion of this renewable resource to carbon fibers, polymers, commodity chemicals, and fuels.
Abstract: Background Lignin, nature’s dominant aromatic polymer, is found in most terrestrial plants in the approximate range of 15 to 40% dry weight and provides structural integrity. Traditionally, most large-scale industrial processes that use plant polysaccharides have burned lignin to generate the power needed to productively transform biomass. The advent of biorefineries that convert cellulosic biomass into liquid transportation fuels will generate substantially more lignin than necessary to power the operation, and therefore efforts are underway to transform it to value-added products. Production of biofuels from cellulosic biomass requires separation of large quantities of the aromatic polymer lignin. In planta genetic engineering, enhanced extraction methods, and a deeper understanding of the structure of lignin are yielding promising opportunities for efficient conversion of this renewable resource to carbon fibers, polymers, commodity chemicals, and fuels. [Credit: Oak Ridge National Laboratory, U.S. Department of Energy] Advances Bioengineering to modify lignin structure and/or incorporate atypical components has shown promise toward facilitating recovery and chemical transformation of lignin under biorefinery conditions. The flexibility in lignin monomer composition has proven useful for enhancing extraction efficiency. Both the mining of genetic variants in native populations of bioenergy crops and direct genetic manipulation of biosynthesis pathways have produced lignin feedstocks with unique properties for coproduct development. Advances in analytical chemistry and computational modeling detail the structure of the modified lignin and direct bioengineering strategies for targeted properties. Refinement of biomass pretreatment technologies has further facilitated lignin recovery and enables catalytic modifications for desired chemical and physical properties. Outlook Potential high-value products from isolated lignin include low-cost carbon fiber, engineering plastics and thermoplastic elastomers, polymeric foams and membranes, and a variety of fuels and chemicals all currently sourced from petroleum. These lignin coproducts must be low cost and perform as well as petroleum-derived counterparts. Each product stream has its own distinct challenges. Development of renewable lignin-based polymers requires improved processing technologies coupled to tailored bioenergy crops incorporating lignin with the desired chemical and physical properties. For fuels and chemicals, multiple strategies have emerged for lignin depolymerization and upgrading, including thermochemical treatments and homogeneous and heterogeneous catalysis. The multifunctional nature of lignin has historically yielded multiple product streams, which require extensive separation and purification procedures, but engineering plant feedstocks for greater structural homogeneity and tailored functionality reduces this challenge.
2,958 citations
TL;DR: This review provides a “beginning‐to‐end” analysis of the recent advances reported in lignin valorisation, with particular emphasis on the improved understanding of lign in's biosynthesis and structure.
Abstract: Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine-tuning of multiple "upstream" (i.e., lignin bioengineering, lignin isolation and "early-stage catalytic conversion of lignin") and "downstream" (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a "beginning-to-end" analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.
1,390 citations
TL;DR: A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provides guidance for future HER mechanism studies on non-noble metal-based carbon composites.
Abstract: Hydrogen has been hailed as a clean and sustainable alternative to finite fossil fuels in many energy systems. Water splitting is an important method for hydrogen production in high purity and large quantities. To accelerate the hydrogen evolution reaction (HER) rate, it is highly necessary to develop high efficiency catalysts and to select a proper electrolyte. Herein, the performances of non-noble metal-based carbon composites under various pH values (acid, alkaline and neutral media) for HER in terms of catalyst synthesis, structure and molecular design are systematically discussed. A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provide guidance for future HER mechanism studies on non-noble metal-based carbon composites. Furthermore, this Review gives a fresh impetus to rational design of high-performance noble-metal-free composites catalysts and guide researchers to employ the established electrocatalysts in proper water electrolysis technologies.
1,258 citations