Self‐Assembly of Hierarchical Ni‐Mo‐Polydopamine Microflowers and their Conversion to a Ni‐Mo2C/C Composite for Water Splitting
TL;DR: With the aim of finding efficient non-noble metal catalysts for water splitting, hierarchical Ni-Mo-polydopamine microflowers were synthesized through a facile aqueous-phase reaction at room temperature, and the nanosized Ni-doped particles offer more active sites and enhance the kinetic performance.
Abstract: With the aim of finding efficient non-noble metal catalysts for water splitting, hierarchical Ni-Mo-polydopamine microflowers (Ni-Mo2 C/C MF) were synthesized through a facile aqueous-phase reaction at room temperature. NiMoO4 nanowires were utilized as both Ni and Mo source; they can complex with dopamine to form a hierarchical structure and affect the scale of the final product. The energy dispersive spectroscopy (EDS) measurement of Ni-Mo2 C/C microflowers (MF) shows a high content of Mo2 C and Ni (>90 wt %). For the hydrogen evolution reaction (HER), the Ni-Mo2 C/C MF displays a low overpotential of 99 mV at a current density of -10 mA cm-2 and a small Tafel slope of 73 mV dec-1 in 1.0 m KOH. By comparison with Mo2 C/C microspheres (MS), the nanosized Ni-doped particles offer more active sites and enhance the kinetic performance. This facile synthesis strategy is also suitable for preparing other metal-Mo2 C/C composites that can be used in the fields of catalysis and energy conversion.
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TL;DR: Specific nanostructures and carbon-based hybrids are introduced to increase active-site abundance and to promote mass transportation, and heteroatom doping and heterointerface engineering are encouraged to optimize the chemical configurations of active sites toward intrinsically boosted HER kinetics.
Abstract: As the key of hydrogen economy, electrocatalytic hydrogen evolution reactions (HERs) depend on the availability of cost-efficient electrocatalysts. Over the past years, there is a rapid rise in noble-metal-free electrocatalysts. Among them, transition metal carbides (TMCs) are highlighted due to their structural and electronic merits, e.g., high conductivity, metallic band states, tunable surface/bulk architectures, etc. Herein, representative efforts and progress made on TMCs are comprehensively reviewed, focusing on the noble-metal-like electronic configuration and the relevant structural/electronic modulation. Briefly, specific nanostructures and carbon-based hybrids are introduced to increase active-site abundance and to promote mass transportation, and heteroatom doping and heterointerface engineering are encouraged to optimize the chemical configurations of active sites toward intrinsically boosted HER kinetics. Finally, a perspective on the future development of TMC electrocatalysts is offered. The overall aim is to shed some light on the exploration of emerging materials in energy chemistry.
459 citations
TL;DR: In this paper, a bamboo-structured nitrogen-doped carbon nanotube coencapped with metallic cobalt and Mo2C nanoparticles is designed and synthesized by a successive pyrolysis approach and demonstrated to be an efficient and stable bifunctional electrocatalyst for overall water splitting in alkaline medium.
Abstract: Developing efficient bifunctional electrocatalysts based on inexpensive and earth-abundant materials for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is essential for large-scale renewable energy storage and conversion processes but remains a major challenge. In this study, a bamboo-structured nitrogen-doped carbon nanotube coencapsulated with metallic cobalt and Mo2C nanoparticles (Co–Mo2C@NCNT) is designed and synthesized by a successive pyrolysis approach and demonstrated to be an efficient and stable bifunctional electrocatalyst for overall water splitting in alkaline medium. Attributing to favorable synergy interaction in composition and structure, the resultant Co–Mo2C@NCNT presents the superior performances toward HER, OER, and even overall water splitting in alkaline medium. To drive a current density of 10 mA cm–2, it needs only an overpotential of ∼186 and ∼377 mV for the electrocatalytic HER and OER, respectively, and a relatively low cell voltage (∼1.628 V) for overall...
142 citations
13 Mar 2021
TL;DR: In this article, a review of 3D hierarchical carbon-rich micro-/nanomaterials (3D HCMNs) is presented, including 3D nanocarbons, polymers, COFs/MOFs, templated carbons and derived carbon-based hybrids with a focus on 3D superstructures.
Abstract: Increasing concerns over climate change and energy shortage have driven the development of clean energy devices such as batteries, supercapacitors, fuel cells and solar water splitting in the past decades. And among potential device materials, 3D hierarchical carbon-rich micro-/nanomaterials (3D HCMNs) have come under intense scrutiny because they can prevent the stacking and bundling of low-dimensional building blocks to not only shorten diffusion distances for matter and charge to achieve high-energy-high-power storage but also greatly expose active sites to achieve highly active, durable and efficient catalysis. Based on this, this review will summarize the synthetic strategies and formation mechanisms of 3D HCMNs, including 3D nanocarbons, polymers, COFs/MOFs, templated carbons and derived carbon-based hybrids with a focus on 3D superstructures such as urchins, flowers, hierarchical tubular structures as well as nanoarrays including nanotube, nanofiber and nanosheet arrays. This review will also discuss the application of 3D HCMNs in energy storage and catalysis systems, including batteries, supercapacitors, electrocatalysis and photo(electro)catalysis. Overall, this review will provide a comprehensive overview of the recent progress of 3D HCMNs in terms of preparation strategies, formation mechanisms, structural diversities and electrochemical applications to provide a guideline for the rational design and structure–function exploration of 3D hierarchical nanomaterials from different sources beyond carbon-based species.
82 citations
TL;DR: In this paper, a typical metal-semiconductor heterostructure with metallic Mo and Mo2C nanoparticles encapsulated in nitrogen-doped carbon nanofibers (N-CNFs) is fabricated via pyrolysis of electrospun polyacrylonitrile (PAN)/cellulose acetate (CA)/bis(acetylacetonato)dioxomolybdenum (MoO2(acac)2)2).
48 citations
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TL;DR: Inspired by the composition of adhesive proteins in mussels, dopamine self-polymerization is used to form thin, surface-adherent polydopamine films onto a wide range of inorganic and organic materials, including noble metals, oxides, polymers, semiconductors, and ceramics.
Abstract: We report a method to form multifunctional polymer coatings through simple dip-coating of objects in an aqueous solution of dopamine. Inspired by the composition of adhesive proteins in mussels, we used dopamine self-polymerization to form thin, surface-adherent polydopamine films onto a wide range of inorganic and organic materials, including noble metals, oxides, polymers, semiconductors, and ceramics. Secondary reactions can be used to create a variety of ad-layers, including self-assembled monolayers through deposition of long-chain molecular building blocks, metal films by electroless metallization, and bioinert and bioactive surfaces via grafting of macromolecules.
8,669 citations
TL;DR: The biggest challenge is whether or not the goals need to be met to fully utilize solar energy for the global energy demand can be met in a costeffective way on the terawatt scale.
Abstract: Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2
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TL;DR: Recent developments in the search for innovative materials with high hydrogen-storage capacity are presented.
Abstract: Mobility — the transport of people and goods — is a socioeconomic reality that will surely increase in the coming years. It should be safe, economic and reasonably clean. Little energy needs to be expended to overcome potential energy changes, but a great deal is lost through friction (for cars about 10 kWh per 100 km) and low-efficiency energy conversion. Vehicles can be run either by connecting them to a continuous supply of energy or by storing energy on board. Hydrogen would be ideal as a synthetic fuel because it is lightweight, highly abundant and its oxidation product (water) is environmentally benign, but storage remains a problem. Here we present recent developments in the search for innovative materials with high hydrogen-storage capacity.
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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