Spiro-based triphenylamine molecule with steric structure as a cathode material for high-stable all organic lithium dual-ion batteries

Redox p-type organic compounds are promising cathode materials for dual-ion batteries.However,the triphenylamine-based polymers usually with agglomerate and intertwined molecular chain nature limit the maximum reaction of their active sites with large-sized anions.Herein,we demonstrate the application of a small molecule with rigid spirofluorene structu re,namely 2,2’,7,7’-tetrakis(diphenylamine)-9,9’-spirobifluorene(Spiro-TAD),as a cathode material for lithium dual-ion batteries.The inherent sterical structure endows the Spiro-TAD with good chemical stability and large internal space for fast diffusion kinetics of anions in the organic electrolyte.As a result,the Spiro-TAD electrode shows significant insolubility and less steric hindrance,and gives a high actual capacity of 109 mA h g^(-1)(active groups utilization ratio approximately 100%) at 50 mA g^(-1)with a high discharge voltage of 3.6 V(vs.Li+/Li),excellent rate capability(60 mA h g^(-1)at 2000 mA g^(-1)) and extremely stable cycling life(98.4% capacity retention after 1400 cycles at 500 mA g^(-1)) in half cells.Such good electrochemical performance is attributed to the robust and rapid adsorption/desorption of ClO4-anions,which can be proved by the in-situ FTIR and XPS.Moreover,an all-organic lithium dual-ion battery(a-OLDIBs) is constructed using the Spiro-TAD as cathode and 3,4,9,10-Perylenetetracarboxylic diimide(PTCDI) as anode and displays long-term cycling performance of 87.5 mA h g^(-1)after 800 cycles.This study will stimulate further developments in designing all organic battery systems.

Single‐atomic Co‐B_(2)N_(2)sites anchored on carbon nanotube arrays promote lithium polysulfide conversion in lithium-sulfur batteries

Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.

Engineering active sites of cathodic materials for high-performance Zn-nitrogen batteries

As an ideal carbon-free energy carrier,ammonia plays an indispensable role in modern society.The conventional industrial synthesis of NH3 by the Haber-Bosch technique under harsh reaction conditions results in serious energy consumption and environmental pollution.Therefore,it is essential to develop NH3 synthesis tactics under benign conditions.Electrochemical synthesis of NH_(3) has the advantages of mild reaction conditions and environmental friendliness,and has become a hotspot for research in recent years.It has been reported that zinc-nitrogen batteries(ZNBs),such as Zn-N_(2),Zn-NO,Zn-NO_(3)^(-),and Zn-NO_(2)^(-)batteries,can not only reduce nitrogenous species to ammonia but also have concomitant power output.However,the common drawbacks of these battery systems are unsatisfactory power density and ammonia production.In this review,the latest progress of ZNBs including the reaction mechanism of the battery and reactor design principles is systematically summarized.Subsequently,active site engineering of cathode catalysts is discussed,including vacancy defects,chemical doping,and heterostructure engineering.Finally,some insights are provided to improve the performance of ZNBs from a practical perspective of view.

Efficiency Enhancement of MEH-PPV:PCBM Solar Cells by Addition of Ditertutyl Peroxide as an Additive

Improved power conversion efficiency(PCE)and stability of organic bulk heterojunction(BHJ)solar cells based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene)(MEH-PPV)and methanofullerene[6,6]-phenyl C_(61)-butyric acid methyl ester(PCBM)blends are obtained by using ditert butyl peroxide(DTBP)as an additive.The effect of the DTBP contents on the performance of photovoltaic cells is investigated.The results reveal that efficiency enhancement of MEH-PPV:PCBM solar cells can be realized by carefully tuning the contents of DTBP.Compared to the control device,the optimized device with 0.5wt%DTBP additive exhibits enhanced performance with Jsc of(3.51±0.21)mA/cm^(2),FF of(44.45±0.71)%,and PCE of(1.31±0.08)%,increased by 9.3%,8.0%and 22.4%,respectively.The stability of the device is found to be improved by adding 0.5wt%of DTBP.

Preparation and luminescent properties of MgTiO_3:Eu^(3+) phosphor for white LEDs

A novel red phosphor Eu3＋ doped magnesium titanate （MgTiO3） was synthesized via sol-gel method. The X-ray diffraction patterns （XRD） revealed that a pure MgTiO3 phase was obtained. Its excitation spectrum consisted of a broad band （〈350nm） and a series of narrow bands in the long wavelength, and the strongest excitation peak at 465nm might be exited by GaN-chip to emit red light for white LED. The phosphors showed strong emission at 614nm which could be attributed to the 5D0→7F2 emission of Eu3＋ . The emission intensity of MgTiO3：Eu3＋ phosphor reached the maximum at the Eu3＋ concentration of 3.5mol.%. The luminescent properties （such as emission intensity and decay times） were further improved by introducing Al3＋ as a charge compensator, demonstrating potential applications in white LED.

Integration of partially phosphatized bimetal centers into trifunctional catalyst for high-performance hydrogen production and flexible Zn-air battery

The development of robust and efficient trifunctional catalysts showing excellent oxygen evolution reaction(OER), oxygen reduction reaction(ORR) and hydrogen evolution reaction(HER) kinetics has been challenging.Herein, we prepared a hybrid iron and cobalt-based metal alloy phosphide on a phosphorus and nitrogen co-doped carbon substrate(Fe Co-P/PNC) as a catalyst using a one-step Pregulation method. The catalyst exhibited a positive half-wave potential of 0.86 V versus the reversible hydrogen electrode(RHE) for ORR, and low overpotentials of 350 and 158 m V for OER and HER, respectively, to achieve a current density of10 m A cm^(-2). Density functional theory calculations demonstrated the dominant role of P in both Fe Co phosphide and carbon matrix, which led to the good ORR, OER and HER kinetics. The assembled aqueous and flexible Zn-air batteries with Fe Co-P/PNC as the air cathode displayed excellent peak power densities of 195.1 and 90.8 m W cm^(-2), respectively, as well as outstanding charging-discharging performance, long lifetime, and high flexibility. Moreover, the self-powered overall water-splitting cell exhibited a low working voltage of1.71 V to achieve a current density of 10 m A cm^(-2), confirming its excellent multifunctional OER/ORR/HER activity.

Highly dispersed Ag clusters for active and stable hydrogen peroxide production

The electrosynthesis of hydrogen peroxide(H2O2)from oxygen reduction reaction(ORR)via a two-electron pathway provides an appealing alternative to the energy-intensive anthraquinone route;however,the development of ORR with high selectivity and durability for H2O2 production is still challenging.Herein,we demonstrate an active and stable catalyst,composing of highly dispersed Ag nanoclusters on N-doped hollow carbon spheres(NC-Ag/NHCS),which can effectively reduce O2 molecules into H2O2 with a selectivity of 89%–91%in a potential range from 0.2 to 0.7 V(vs.reversible hydrogen electrode(RHE))in acidic media.Strikingly,NC-Ag/NHCS achieve a mass activity of 27.1 A·g^(−1) and a yield rate of 408 mmol·gcat.^(−1)·h^(−1) at 0.7 V,both of which are comparable with the best-reported results.Furthermore,NC-Ag/NHCS enable catalyzing H2O2 production with a stable current density over 48-h electrolysis and only about 9.8%loss in selectivity after 10,000 cycles.Theoretical analyses indicate that Ag nanoclusters can contribute more electrons to favor the protonation of adsorbed O2,thus leading to a high H2O2 selectivity.This work confirms the great potential of metal nanocluster-based materials for H2O2 electrosynthesis under ambient conditions.

Hollow CoFe-layered double hydroxide polyhedrons for highly efficient CO_(2) electrolysis

Over the past several decades,the utilization of fossil fuels is responsible for mainly excessive atmospheric carbon dioxide(CO_(2))[1-3].Increased concentration of CO_(2)contributes to the major portion of the critical issues faced worldwide,such as global warming and drastic changes in climate.Therefore,it is imperative to develop an alternative technology that is capable of providing an efficient and sustainable pathway to target the neutralization of CO_(2)level in the atmosphere.

A green method for synthesizing novel nanoparticles and their application in flexible conductive patterns

A general and unified approach to synthesize Ag,Cu and Au nanoparticles(NPs)is developed at room temperature in air atmosphere under ultrasonication in poly(N-vinylpyrrolidone)(PVP)solutions with ascorbic acid and glucose as the reducing and nucleation agents,respectively.XRD,TEM,and HR-TEM analysis of the Ag,Cu,and Au NPs confirm purity and average diameters of 15.5±2.0 nm,50±3.0 nm,and 10±1.0 nm,respectively.An ultrasonic-assisted mechanism,wherein reduction occurs readily and produces anti-oxidation particles,is proposed and discussed.Fast infrared sintering was used to avoid damaging the substrate of conductive patterns whose resistivity at 10 W(~50℃)sintering power for less than 6 min reached up to 10±0.5 μΩ cm,40±3.0 μΩ cm,and 280±5 μΩ cm for Ag,Cu,and Au patterns,respectively.Paper-based electrodes were produced successfully and exhibited excellent flexibility and good conductivity.The potential of this method for large scale production is discussed.

Electrocatalytic reduction of NO to NH_(3) in ionic liquids by P-doped TiO_(2) nanotubes

Designing advanced and cost-effective electrocatalytic system for nitric oxide(NO)reduction reaction(NORR)is vital for sustainable NH_(3) production and NO removal,yet it is a challenging task.Herein,it is shown that phosphorus(P)-doped titania(TiO_(2))nanotubes can be adopted as highly efficient catalyst for NORR.The catalyst demonstrates impressive performance in ionic liquid(IL)-based electrolyte with a remarkable high Faradaic efficiency of 89%and NH3 yield rate of 425μg·h^(−1)·mg_(cat).^(−1),being close to the best-reported results.Noteworthy,the obtained performance metrics are significantly larger than those for N_(2) reduction reaction.It also shows good durability with negligible activity decay even after 10 cycles.Theoretical simulations reveal that the introduction of P dopants tunes the electronic structure of Ti active sites,thereby enhancing the NO adsorption and facilitating the desorption of ^(*)NH_(3).Moreover,the utilization of IL further suppresses the competitive hydrogen evolution reaction.This study highlights the advantage of the catalyst−electrolyte engineering strategy for producing NH_(3) at a high efficiency and rate.

双功能Nb-N-C原子分散催化剂用于水系锌-空气电池驱动CO_(2)还原

设计廉价和高效的双功能催化剂应用于CO_(2)还原和O_(2)还原反应(CO_(2)RR和ORR)是实现碳中和的理想选择.因此,本文研制出铌原子分散固定在氮掺杂有序介孔碳(Nb-N-C)上的双功能CO_(2)RR和ORR催化剂用于锌-空气电池(ZAB)自驱动CO_(2)RR.得益于高铌原子利用率和有序介孔结构,Nb-N-C催化剂展现出高达90%的CO法拉第效率,ORR的半波电位活性为0.84 V,ZAB的峰值功率活性为115.6 mW cm-2.此外,采用两个串联的ZABs单元作为自供能CO_(2)RR系统的电源,能够连续将C O_(2)转化为C O.该自供能系统前10小时的C O平均产率为3.75μmol h-1mg-1cat.理论计算表明,铌原子分散固定在氮掺杂的碳上形成Nb–N配位键,从而有效地降低CO_(2)RR的决速中间体*COOH和ORR的决速中间体*O的生成能垒.

MoC nanocrystals confined in N-doped carbon nanosheets toward highly selective electrocatalytic nitric oxide reduction to ammonia

Electrochemical nitric oxide reduction reaction(NORR)to produce ammonia(NH3)under ambient conditions is a promising alternative to the energy and carbon-intensive Haber–Bosch approach,but its performance is still improved.Herein,molybdenum carbides(MoC)nanocrystals confined by nitrogen-doped carbon nanosheets are first designed as an efficient and durable electrocatalyst for catalyzing the reduction of NO to NH3 with maximal Faradaic efficiency of 89%±2%and a yield rate of 1,350±15μg·h^(−1)·cm^(−2) at the applied potential of−0.8 V vs.reversible hydrogen electrode(RHE)as well as high stable activity with negligible current density and NH3 yield rate decays over a 30 h continue the test.Moreover,as a proof-of-concept of Zn–NO battery,it achieves a peak power density of 1.8 mW·cm^(−2) and a large NH3 yield rate of 782±10μg·h^(−1)·cm^(−2),which are comparable to the best-reported results.Theoretical calculations reveal that the MoC(111)has a strong electronic interaction with NO molecules and thus lowering the energy barrier of the potential-determining step and suppressing hydrogen evolution kinetics.This work suggests that Mo-based materials are a powerful platform providing great opportunities to explore highly selective and active catalysts for NH3 production.

High-efficiency electrocatalytic NO reduction to NH_(3) by nanoporous VN

Electrocatalytic NO reduction reaction to generate NH_(3)under ambient conditions offers an attractive alternative to the energy-extensive Haber-Bosch route;however,the challenge still lies in the development of cost-effective and high-performance electrocatalysts.Herein,nanoporous VN film is first designed as a highly selective and stable electrocatalyst for catalyzing reduction of NO to NH_(3)with a maximal Faradaic efficiency of 85%and a peak yield rate of 1.05×10^(-7)mol·cm^(-2)·s^(-1)(corresponding to 5,140.8mg·h^(-1)·mg_(cat).^(-1))at-0.6 V vs.reversible hydrogen electrode in acid medium.Meanwhile,this catalyst maintains an excellent activity with negligible current density and NH_(3)yield rate decays over 40 h.Moreover,as a proof-of-concept of Zn-NO battery,it delivers a high power density of 2.0 mW·cm^(-2)and a large NH_(3)yield rate of 0.22×10^(-7)mol·cm^(-2)·s^(-1)(corresponding to 1,077.1mg·h^(-1)·mg_(cat).^(-1)),both of which are comparable to the best-reported results.Theoretical analyses confirm that the VN surface favors the activation and hydrogenation of NO by suppressing the hydrogen evolution.This work highlights that the electrochemical NO reduction is an eco-friendly and energy-efficient strategy to produce NH_(3).