Hierarchical Interconnected NiMoN with Large Specific Surface Area and High Mechanical Strength for Efficient and Stable Alkaline Water/Seawater Hydrogen Evolution

NiMo-based nanostructures are among the most active hydrogen evolution reaction(HER)catalysts under an alkaline environment due to their strong water dissociation ability.However,these nanostructures are vulnerable to the destructive effects of H_(2) production,especially at industry-standard current densities.Therefore,developing a strategy to improve their mechanical strength while maintaining or even further increasing the activity of these nanocatalysts is of great interest to both the research and industrial communities.Here,a hierarchical interconnected NiMoN(HW-NiMoN-2h)with a nanorod-nanowire morphology was synthesized based on a rational combination of hydrothermal and water bath processes.HW-NiMoN-2h is found to exhibit excellent HER activity due to the accomodation of abundant active sites on its hierarchical morphology,in which nanowires con-nect free-standing nanorods,concurrently strengthening its structural stability to withstand H_(2) production at 1 A cm^(−2).Seawater is an attractive feedstock for water electrolysis since H_(2) generation and water desalination can be addressed simultaneously in a single process.The HER performance of HW-NiMoN-2h in alkaline seawater suggests that the presence of Na+ions interferes with the reation kinetics,thus lowering its activity slightly.However,benefiting from its hierarchical and interconnected characteristics,HW-NiMoN-2h is found to deliver outstanding HER activity of 1 A cm^(−2) at 130 mV overpotential and to exhibit excellent stability at 1 A cm^(−2) over 70 h in 1 M KOH seawater.

Enhancing I^(0)/I^(-)Conversion Efficiency by Starch Confinement in Zinc-lodine Battery

The redox couple of I^(0)/I^(-)in aqueous rechargeable iodine–zinc(I^(2)-Zn)batteries is a promising energy storage resource since it is safe and cost-effective,and provides steady output voltage.However,the cycle life and efficiency of these batteries remain unsatisfactory due to the uncontrolled shuttling of polyiodide(I_(3)^(-)and I_(5)^(-))and side reactions on the Zn anode.Starch is a very low-cost and widely sourced food used daily around the world.“Starch turns blue when it encounters iodine”is a classic chemical reaction,which results from the unique structure of the helix starch molecule–iodine complex.Inspired by this,we employ starch to confine the shuttling of polyiodide,and thus,the I^(0)/I^(-)conversion efficiency of an I^(2)-Zn battery is clearly enhanced.According to the detailed characterizations and theoretical DFT calculation results,the enhancement of I^(0)/I^(-)conversion efficiency is mainly originated from the strong bonding between the charged products of I_(3)^(-)and I_(5)^(-)and the rich hydroxyl groups in starch.This work provides inspiration for the rational design of high-performance and low-cost I^(2)-Zn in AZIBs.

High thermoelectric performance at room temperature of n-type Mg_(3)Bi_(2)-based materials by Se doping

Bi_(2)Te_(3) based alloys have been the most widely used thermoelectric material at low temperature for many decades.Here we report Se doped n-type Mg_(3)Bi_(2) based materials with a thermoelectric figure-of-merit ZT of 0.82 at 300 K and a peak ZT of 1.24 at 498 K,which is comparable to the n-type Bi_(2)Te_(3) and Te doped Mg_(3)Bi_(1.4)Sb_(0.6).The improved thermoelectric performance is benefited from the high carrier concentration and mobility as well as the thermal conductivity reduction.The reduced resistivity increased the power factor at all measured temperatures,leading to a higher engineering ZT(ZTeng)and engineering power factor(PFeng)for n-type Mg_(3)Bi_(2).The n-type Mg_(3)Bi_(1.4)Sb_(0.6) materials are promising for thermoelectric power generation and cooling applications near room temperature.

Research progress on synthesis of zeolites from coal fly ash and environmental applications

The by-product of coal combustion,coal fly ash(CFA),has become one of the world’s most emitted solid wastes,and bulk utilization while achieving high value-added products is the focus of current research.Using CFA to prepare zeolite cannot only reduce environmental pressure,but also obtain high value-added products,which has a good market prospect.In this paper,the research progress of hydrothermal synthesis method of CFA zeolites is reviewed in detail and summarized several other synthetic methods of CFA zeolites.This review also presents an overview of CFA zeolites application in environmental applications like water treatment,gas adsorption and soil remediation.However,a considerable number of literature data have documented using CFA zeolites for water treatment,whereas research on CFA zeolites application to gas adsorption and soil remediation is still limited.In addition,the current status of basic research on the industrial production of CFA zeolites is briefly summarized,and the development trend of the synthetic zeolite of CFA is prospected.After the feasibility analysis of the industrial production of CFA zeolite,it is concluded that the only two methods with high feasibility for industrial application are two-step hydrothermal and alkali melting methods,and the industrial production technology still needs to be studied in depth.

不同弓形浸渍管RH钢液流动行为的物理模拟

为提高真空循环脱气(RH)真空精炼的效率,设计了3种新型弓形浸渍管RH真空室,并建立了物理模型。通过水模拟实验研究了浸渍管形状、提升气体流量、浸渍管浸入钢液深度对弓形浸渍管RH和传统圆形浸渍管RH钢液循环流动的影响。结果表明,在实验气体流量范围内,3个弓形浸渍管RH比传统圆形浸渍管RH的循环流量增加了45%~218%,均混时间减少了15%以上。圆形浸渍管RH达最大吹气流量时,3种弓形浸渍管RH的循环流量仍线性增加。新型弓形浸渍管RH的最大提升气体流量可在传统圆形浸渍管RH提升气体流量(60?130 m^3/h)的基础上提高48%以上,方便短时间、高强度真空精炼操作。3种新型弓形浸渍管RH的循环流量随提升气体流量增加而线性增大,随浸渍管浸入钢液深度增加而增大,均混时间随提升气体流量和浸入深度增加而减小。现场应用时,弓形浸渍管其中2个面积较小的浸渍管浸入深度须大于545 mm,面积最大的浸入深度须大于818mm,3个弓形浸渍管RH的最大提升气体流量需控制在约173m^3/h。在现场现行的提升气体流量范围(60~130Nm^3/h)内,1#, 2#和3#弓形浸渍管RH的循环流量较传统圆形浸渍管RH分别约增加100%, 42%和112%,均混时间分别缩短30%, 15%和34%以上。在实验提升气体流量范围内,非对称弓形浸渍管RH的循环流量最大,均混时间最少。

Metallic nanostructures for light trapping in energy-harvesting devices

Solar energy is abundant and environmentally friendly.Light trapping in solar-energy-harvesting devices or structures is of critical importance.This article reviews light trapping with metallic nanostructures for thin film solar cells and selective solar absorbers.The metallic nanostructures can either be used in reducing material thickness and device cost or in improving light absorbance and thereby improving conversion efficiency.The metallic nanostructures can contribute to light trapping by scattering and increasing the path length of light,by generating strong electromagnetic field in the active layer,or by multiple reflections/absorptions.We have also discussed the adverse effect of metallic nanostructures and how to solve these problems and take full advantage of the light-trapping effect.

Recent Advances in Self-Supported Layered Double Hydroxides for Oxygen Evolution Reaction

Electrochemical water splitting driven by clean and sustainable energy sources to produce hydrogen is an efficient and environmentally friendly energy conversion technology.Water splitting involves hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),in which OER is the limiting factor and has attracted extensive research interest in the past few years.Conventional noble-metal-based OER electrocatalysts like IrO_(2) and RuO_(2) suffer from the limitations of high cost and scarce availability.Developing innovative alternative nonnoble metal electrocatalysts with high catalytic activity and long-term durability to boost the OER process remains a significant challenge.Among all of the candidates for OER catalysis,selfsupported layered double hydroxides(LDHs)have emerged as one of the most promising types of electrocatalysts due to their unique layered structures and high electrocatalytic activity.In this review,we summarize the recent progress on self-supported LDHs and highlight their electrochemical catalytic performance.Specifically,synthesis methods,structural and compositional parameters,and influential factors for optimizing OER performance are discussed in detail.Finally,the remaining challenges facing the development of self-supported LDHs are discussed and perspectives on their potential for use in industrial hydrogen production through water splitting are provided to suggest future research directions.

Thermoelectric properties of silicon and recycled silicon sawing waste

Large-scale-applicable thermoelectric materials should be both self-sustaining,in order to survive longterm duty cycles,and nonpolluting.Among all classes of known thermoelectric materials,these criteria reduce the available candidate pool,leaving silicon as one of the remaining options.Here we first review the thermoelectric properties of various silicon-related materials with respect to their morphologies and microstructures.We then report the thermoelectric properties of silicon sawing wastes recycled from silicon wafer manufacturing.We obtain a high power factor of~32 mWcm
1 K
2 at 1273 K with 6%phosphorus substitution in the Si crystal,a value comparable to that of phosphorus-doped silicongermanium alloys.Our work suggests the large-scale thermoelectric applicability of recycled silicon that would otherwise contribute to the millions of tons of industrial waste produced by the semiconductor industry.

N-Type Mg_(3)Sb_(2-x)Bi_(x) Alloys as Promising Thermoelectric Materials

N-type Mg_(3)Sb_(2-x)Bi_(x) alloys have been extensively studied in recent years due to their significantly enhanced thermoelectric figure of merit(zT),thus promoting them as potential candidates for waste heat recovery and cooling applications.In this review,the effects resulting from alloying Mg_(3)Bi_(2) with Mg_(3)Sb_(2),including narrowed bandgap,decreased effective mass,and increased carrier mobility,are summarized.Subsequently,defect-controlled electrical properties in n-type Mg_(3)Sb_(2-x)Bi_(x) are revealed.On one hand,manipulation of intrinsic and extrinsic defects can achieve optimal carrier concentration.On the other hand,Mg vacancies dominate carrier-scattering mechanisms(ionized impurity scattering and grain boundary scattering).Both aspects are discussed for Mg_(3)Sb_(2-x)Bi_(x) thermoelectric materials.Finally,we review the present status of,and future outlook for,these materials in power generation and cooling applications.

Anomalous CDW ground state in Cu_(2)Se:A wave-like fluctuation of the dc I-v curve near 50 K

A charge density wave(CDW)ground state is observed in polycrystalline Cu_(2)Se below 125 K,which corresponds to an energy gap of 40.9 meV and an electron-phonon coupling constant of 0.6.Due to the polycrystalline structure,the Peierls transition process has been expanded to a wide temperature range from 90 K to 160 K.The Hall carrier concentration shows a continuous decrease from 2.1×10^(20)to 1.6×10^(20)cm^(-3)in the temperature range from 160 K to 90 K,while almost unchanged above 160 K and below 90 K.After entering the CDW ground state,a wave-like fluctuation was observed in theI-Vcurve near 50 K,which exhibits a periodic negative differential resistivity in an applied electric field due to the current.We also investigated the doping effect of Zn,Ni,and Te on the CDWground state.Both Zn and Ni doped Cu_(2)Se show a CDW character with increased energy gap and electron-phonon coupling constant,but no notable Peierls transition was observed in Te doped Cu_(2)Se.Similar wave-likeI-Vcurve was also seen in Cu_(1.98)Zn_(0.02)Se near 40 K.The regular fluctuation in the dcI-Vcurve was not magnetic field sensitive,but temperature and sample size sensitive.