The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides a feasible approach for the efficient utilization of biomass. Defect regulation is an effective strategy in the field of biomass upgrading to enhance the adsorption capacity of reactants and thus increase the activity. However, how to select appropriate strategies to regulate the over-enrichment of reactants induced by excessive oxygen vacancy is still a huge challenge.
View Article and Find Full Text PDFThe electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides a feasible way for utilization of biomass resources. However, how to regulate the selective synthesis of multiple value-added products is still a great challenge. The cobalt-based compound is a promising catalyst due to its direct and indirect oxidation properties, but its weak adsorption capacity restricts its further development.
View Article and Find Full Text PDFElectrocatalytic urea synthesis through N + CO coreduction and C-N coupling is a promising and sustainable alternative to harsh industrial processes. Despite considerable efforts, limited progress has been made due to the challenges of breaking inert N≡N bonds for C-N coupling, competing side reactions, and the absence of theoretical principles guiding catalyst design. In this study, we propose a mechanism for highly electrocatalytic urea synthesis using two adsorbed N molecules and CO as nitrogen and carbon sources, respectively.
View Article and Find Full Text PDFElectrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides an efficient way to obtain high-value-added biomass-derived chemicals. Compared with other transition metal oxides, CuO exhibits poor oxygen evolution reaction performance, leading to high Faraday efficiency for HMF oxidation. However, the weak adsorption and activation ability of CuO to OH species restricts its further development.
View Article and Find Full Text PDFThe realization of intertwined ferroelasticity and ferromagnetism in two-dimensional (2D) lattices is of great interest for broad nanoscale applications but still remains a remarkable challenge. Here, we propose an alternative approach to realize the strongly coupled ferromagnetism and ferroelasticity by carrier doping. We demonstrate that prototypical 2D β-PbO is dynamically, thermally and mechanically stable.
View Article and Find Full Text PDFIn two-dimensional (2D) hexagonal lattices with inversion asymmetry, time-reversal () connected valleys are at the center of current valleytronic research. In order to trigger valley polarization, dynamical processes and/or magnetism have been considered. In this work, we propose a new mechanism, valley-contrasting sublattice polarization (VCSP), to polarize valleys by reducing the crystalline symmetry that connects the valleys.
View Article and Find Full Text PDFACS Appl Mater Interfaces
March 2021
MXenes, an emerging family of two-dimensional (2D) metal carbides and nitrides, have been demonstrated to be effective nitrogen reduction reaction (NRR) catalysts. So far, most of the theoretical studies toward NRR are based on bare MXenes; however, the structural stabilities are questionable. In this work, we studied the NRR process on several synthesized MXenes (TiC, VC, CrC, ZrC, NbC, MoC, HfC, and TaC) with hydroxyl (OH) termination since the structures are preferred under NRR operating conditions as per Pourbaix stability diagrams.
View Article and Find Full Text PDFGreat enthusiasm in single-atom catalysts (SACs) for the nitrogen reduction reaction (NRR) has been aroused by the discovery of metal-N as a promising catalytic center. However, the poor activity and low selectivity of available SACs are far away from the industrial requirement. Through the first-principles high-throughput screening, we find that Fe-Fe distributed on graphite carbon nitride (Fe/-CN) can manipulate the binding strength of the target reaction species (compromises the ability to adsorb NH and NH), therefore achieving the best NRR performance among 23 transition metal (TM) centers.
View Article and Find Full Text PDFDue to the complexity of harmful wastewater components, environmental and multifunctional materials are required for sewage purification. In this paper, a novel kidney-bean-skin-like hydrophilic porous polyacrylonitrile/reduced graphene oxide--poly(amidoxime)-loaded Ag (H-PPAN/rGO--PAO@Ag/Ag) composite nanofiber membrane was fabricated by combining electrospinning and hydrolysis methods. The spinning solution was pumped at a rate of 0.
View Article and Find Full Text PDFHerein, a metal-organic framework (MOF)/polythiophene (PTh)-derived S-doped carbon is successfully designed and prepared employing zeolitic imidazolate frameworks (ZIF-8/ZIF-67) and thiophene (Th) as precursors. The S-doped carbon presents a neuronlike three-dimensional network structure (3DSC). The 3DSC delivers extra-high capacities (225 mAh/g at 5000 mA/g after 3000 cycles) and excellent endurance ability of current changes when applied in Na-ion batteries (SIBs).
View Article and Find Full Text PDFConversion of naturally abundant dinitrogen (N) to ammonia (NH) is one of the most attractive and challenging topics in chemistry. Current studies mainly focus on electrocatalytic nitrogen reduction reaction (NRR) using metal-based electrocatalysts, while metal-free and solar-driven photocatalysts have been rarely explored. Here, on the basis of the "σ donation- back-donation" concept, single B atom supported on holey -CN (B@-CN) can serve as metal-free photocatalyst for highly efficient N fixation and reduction under visible and even infrared spectra.
View Article and Find Full Text PDFThe development of MoS2-based electronic devices is dependent on finding electrode materials suitable for forming Ohmic contacts with MoS2. For this purpose, we carried out density functional theory and nonequilibrium Green's function calculations to investigate the possibility of using pristine and modified MXene (Ta2C/Ta2CF2/Ta2C(OH)2) monolayers as the electrode materials in such devices. These calculations indicated the formation of chemical bonds at the MoS2/Ta2C interface, and resulting strong orbital hybridization between the MoS2 and Ta2C components, but relatively weak interactions for MoS2/Ta2CF2 and MoS2/Ta2C(OH)2.
View Article and Find Full Text PDFAlthough rechargeable lithium-sulfur batteries are considered as advanced energy systems, their practical implementation is impeded by many factors, in particular the rapid capacity fade and low Coulomb efficiency caused by the shuttle effect. To overcome this problem for achieving longer cycle life and higher rate performance, anchoring materials for lithium polysulfides are highly desirable. In this work, for the first time, we report phosphorene-like MX (M=Ge, Sn; X=S, Se) monolayers as promising anchoring materials to restrain the lithium polysulfides shuttling.
View Article and Find Full Text PDFACS Appl Mater Interfaces
June 2018
The short cycle life of lithium-sulfur batteries (LSBs) plagues its practical application. In this study, a uniform SnO/reduced graphene oxide (denoted as SnO/rGO) composite is successfully designed onto the commercial polypropylene separator for use of interlayer of LSBs to decrease the charge-transfer resistance and trap the soluble lithium polysulfides (LPSs). As a result, the assembled devices using the separator modified with the functional interlayer (SnO/rGO) exhibit improved cycle performance; for instance, over 200 cycles at 1C, the discharge capacity of the cells reaches 734 mAh g.
View Article and Find Full Text PDFJ Colloid Interface Sci
September 2018
Constructing organic-inorganic hybrids is one of the hopeful strategies to improve photocatalyst performance. In this study, perylene-3,4,9,10-tetracarboxylic diimide (PDINH) and commercial TiO P25 are chosen as raw materials to construct a PDINH/TiO organic-inorganic hybrid, which has higher photocatalytic H production activity and photocurrent intensity than pure PDINH and TiO, respectively. The apparent quantum efficiency for H production over 0.
View Article and Find Full Text PDFThe performance of electronic and optoelectronic devices based on two-dimensional (2D) materials could be significantly affected by the electrical contacts. In search of low-resistance contacts with transition-metal dichalcogenides (TMDs), we combine density functional calculations with quantum transport simulations to investigate the structural and electronic properties of the van der Waals (vdW) heterostructures MSe/NbSe (M = Mo and W). The formation of a p-type Schottky contact at the MSe/NbSe interface with small Schottky barriers (0.
View Article and Find Full Text PDFPhys Chem Chem Phys
August 2017
The structural and electronic properties of germanene are always strongly modulated by the hybridization effects with metal substrates. In order to see what will happen when a buffer layer is introduced in-between germanene and metal substrates, we study the structural and electronic properties of the recently synthesized monolayer and bilayer germanene on Cu(111) though first-principles calculations. Our results show that the monolayer germanene on Cu(111) displays a nearly flat configuration and interface states form between the Ge p and Cu sp-like states, with the Ge π states maintaining the Dirac character.
View Article and Find Full Text PDFTwo-dimensional (2D) Sc C, an example of a MXene, has been attracting extensive attention due to its distinctive properties and great potential in applications such as energy storage. In light of its high capacity and fast charging-discharging performance, Sc C exhibits significant potential as an anode material for lithium- and sodium-ion batteries. Herein, a systematic investigation of Li/Na atom adsorption and diffusion on Sc C planes was performed based on density functional calculations.
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