Continuous-flow electrosynthesis of urea and oxalic acid by CO_(2)-nitrate reduction and glycerol oxidation

Urea and oxalic acid are critical component in various chemical manufacturing industries.However,achieving simultaneous generation of urea and oxalic acid in a continuous-flow electrolyzer is a challenge.Herein,we report a continuous-flow electrolyzer equipped with 9-square centime-ter-effective area gas diffusion electrodes(GDE)which can simultaneously catalyze the glycerol oxidation reaction in the anode region and the reduction reaction of CO_(2) and nitrate in the cathode region,producing oxalic acid and urea at both the anode and cathode,respectively.The current density at low cell voltage(0.9 V)remained above 18.7 mA cm^(-2) for 10 consecutive electrolysis cycles(120 h in total),and the Faraday efficiency of oxalic acid(67.1%) and urea(70.9%)did not decay.Experimental and theoretical studies show that in terms of the formation of C-N bond at the cathode,Pd-sites can provide protons for the hydrogenation process of CO_(2) and NO_(3)^(-),Cu-sites can promote the generation of *COOH and Bi-sites can stabilize *COOH.In addition,in terms of glycerol oxidation,the introduction of Cu and Bi into Pd metallene promotes the oxidation of hydroxyl groups and the cleavage of C-C bond in glycerol molecules,respectively.

Recent advances in design of hydrogen evolution reaction electrocatalysts at high current density:A review

The electrolysis of water powered by renewable energy sources offers a promising method of"green hydrogen"production,which is considered to be at the heart of future carbon-neutral energy systems.In the past decades,researchers have reported a number of hydrogen evolution reaction(HER)electrocatalysts with activity comparable to that of commercial Pt/C,but most of them are tested within a small current density range,typically no more than 500 mA cm^(-2).To realize the industrial application of hydrogen production from water electrolysis,it is essential to develop high-efficiency HER electrocatalysts at high current density(HCD≥500 mA cm^(-2)).Nevertheless,it remains challenging and significant to rational design HCD electrocatalysts for HER.In this paper,the design strategy of HCD electrocatalysts is discussed,and some HCD electrocatalysts for HER are reviewed in seven categories(alloy,metal oxide,metal hydroxide,metal sulfide/selenide,metal nitride,metal phosphide and other derived electrocatalysts).At the end of this article,we also pro-pose some viewpoints and prospects for the future development and research directions of HCD electrocatalysts for HER.

固相法涂料用HCPE的聚集态和链结构

研究了固相法涂料用高氯化聚乙烯(HCPE)的结构:以差示扫描量热法表征聚集态结构,以傅里叶变换红外光谱(FTIR)和核磁共振氢谱(1H-NMR)表征链结构.结果表明,在ω(Cl)超过55.0%时,HCPE中已无晶区存在;FTIR谱图中同时存在表征氯化不均匀的-CH2CH2CH2-(γ亚甲基)和-CCl2CH2CHCl-(高频α亚甲基),且有脱HCl反应而生成的C=C振动峰;高频α亚甲基在1H-NMR中的化学位移为2.80～3.40;随ω(Cl)的提高,高频α亚甲基含量显著增加;提高原料PE的粒径或适当提高后期氯化温度,可有效改善氯化均匀度;HCPE清漆中的不溶物主要由隔离剂及氯化程度低的氯化聚乙烯构成.

Strategies on improving the electrocatalytic hydrogen evolution performances of metal phosphides

Among the sustainable energy sources,hydrogen is the one most promising for alleviating the pollution issues related to the usage of conventional fuels,as it can be produced in an efficient and eco-friendly way via electrocatalytic water splitting.The hydrogen evolution reaction(HER,a half-reaction of water splitting)plays a pivotal role in decreasing the price and increasing the catalytic efficiency of hydrogen production and is efficiently promoted by metal phosphides in different electrolytes.Herein,we summarize the recent advances in the development of metal phosphides as HER electrocatalysts,focus on their synthesis(post-treatment,in situ generation,and electrodeposition methods)and the enhancement of their electrocatalytic activity(via elemental doping,interface and vacancy engineering,construction of specific supports and nanostructures,and the design of bior polymetallic phosphides),and highlight the crucial issues and challenges of future development.

Metal‐organic framework‐derived multifunctional photocatalysts

Metal‐organic framework(MOF)‐derived nanomaterials have attracted widespread attention,because the excellent features,such as high surface area,porosity and tunable properties are inherited from MOFs.Moreover,the derivatives avoid the poor conductivity and stability of MOFs.MOF‐derived nanomaterials can easily be regulated by a specific selection of metal nodes and organic linkers,resulting in multifunctionality in photocatalysis.MOF derivatives can be used not only as semiconductor photocatalysts,but also as co‐catalysts for photocatalytic hydrogen evolution,CO_(2) reduction,pollutants degradation,etc.This review focuses on the multifunctional applications of MOF derivatives in the field of photocatalysis.The researches in recent years are analyzed and summarized from the aspects of preparation,modification and application of MOF derivatives.At the end of the review,the development and challenges of MOF derivatives applied in photocatalysis in the future are put forward,in order to provide more references for further research in this field and bring new inspiration.

Coralline-like Ni_(2)P decorated novel tetrapod-bundle Cd_(0.9)Zn_(0.1)S ZB/WZ homojunctions for highly efficient visible-light photocatalytic hydrogen evolution

In this study,Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)composites were synthesized by coupling tetrapod bundle Cd_(0.9)Zn_(0.1)S(CZS)and coralline-like Ni_(2)P(NP)via a simple calcination method.CZS shows outstanding activity in photocatalytic hydrogen evolution(1.31 mmol h^(‒1)),owing to its unique morphology and heterophase homojunctions(ZB/WZ),which accelerate the separation and transfer of photogenerated charges.After coupling with NP,the photoactivity of NPCZS was enhanced,and the maximum hydrogen evolution rate of 1.88 mmol h^(‒1)was reached at a NP content of 12 wt%,which was 1.43 times higher than that of pure CZS.The experimental results of the photocatalytic activity,viz.photoluminescence spectra,surface photovoltage spectra,and electrochemical test showed that the enhanced photoactivity of NPCZS should be attributed to the synergistic effects of the novel tetrapod-bundle morphology,heterophase homojunctions,and decoration of the NP co-catalyst.Moreover,the as-prepared NPCZS composites exhibited excellent photostability and recyclability.Herein,we propose a possible mechanism for the enhanced photocatalytic activity.

Controllable synthesis of a self-assembled ultralow Ru,Ni-doped Fe_(2)O_(3) lily as a bifunctional electrocatalyst for large-current-density alkaline seawater electrolysis

Highly efficient and stable bifunctional electrocatalysts that can be used for large-current-density electrolysis of alkaline seawater are highly desirable for carbon-neutral economies,but their facile and controllable synthesis remains a challenge.Here,self-assembled ultralow Ru,Ni-doped Fe_(2)O_(3) with a lily shaped morphology was synthesized on iron foam(RuNi-Fe_(2)O_(3)/IF)via a facile one-step hydrothermal process,in which the intact lily shaped RuNi-Fe_(2)O_(3)/IF was obtained by adjusting the ratio of Ru/Ni.Benefitting from the Ru/Ni chemical substitution,the as-synthesized RuNi-Fe_(2)O_(3)/IF can act as free-standing dual-function electrodes that are applied to electrocatalysis for the hydrogen evolution(HER)and oxygen evolution reactions(OER)in 1.0 mol L^(-1) KOH,requiring an overpotential of 75.0 mV to drive 100 mA cm^(-2) for HER and 329.0 mV for OER.Moreover,the overall water splitting catalyzed by RuNi-Fe_(2)O_(3)/IF only demands ultralow cell voltages of 1.66 and 1.73 V to drive 100 mA cm^(-2) in 1.0 mol L^(-1) KOH and 1.0 mol L^(-1) KOH seawater electrolytes,respectively.The electrodes show remarkable long-term durability,maintaining current densities exceeding 100 mA cm^(-2) for more than 100 h and thus outperforming the two-electrode system composed of noble catalysts.This work provides an efficient,economical method to synthesize self-standing bifunctional electrodes for large-current-density alkaline seawater electrolysis,which is of significant importance for ecological protection and energy exploitation.

Scalable synthesis of ultra‐small Ru_(2)P@Ru/CNT for efficient seawater splitting

In this study,an ultra‐fast and simple solvent‐free microwave method was successfully demonstrated using a series of ultra‐small(~2.5 nm)surfactant‐free Ru_(2)P@Ru/CNT heterostructures for the first time.The structure has a high‐density Ru component and Ru_(2)P component interface,which accelerates the hydrogen evolution reaction(HER).The prepared Ru_(2)P@Ru/CNT demonstrated excellent catalytic effects for the HER in alkaline media and real seawater.The experimental results indicate that ratio‐optimized Ru_(2)P@Ru/CNT(Ru_(2)P:Ru=66:34)requires only 23 and 29 mV to reach 10 mA cm^(-2)in 1.0 mol/L KOH and real seawater,respectively.These values are 10 and 24 mV lower than those of commercial Pt/C in 1.0 mol/L KOH(33 mV)and real seawater(53 mV),respectively,making it among the best non‐Pt HER reported in the literature.Additionally,the TOF of Ru_(2)P@Ru/CNT in alkaline freshwater and seawater were 13.1 and 8.5 s^(-1),respectively.These exceed the corresponding values for Pt/C,indicating that the catalyst has excellent intrinsic activity.The high current activity of Ru_(2)P@Ru/CNT in 1.0 mol/L KOH was explored,and only 77 and 104 mV were required to reach 500 and 1000 mA cm^(-2),respectively.After 100 h of durability testing,the catalyst retained excellent catalytic and structural stability in low current density,high current density,and seawater.

First-Principles Study of Blue Phosphorene and Graphene Intralayer Heterostructure as Anode Materials for Rechargeable Li-lon Batteries

There is an ideal desire to develop the high-performance anodes materials for Liion batteries(LIBs),which requires not onlyhigh stability and reversibility,but also rapidcharging/discharging rate.In this work,webuiltablue phosphorene-graphene(BlueP-G)intralayer heterostructure by connecting BlueP and graphene monolayers at zigzag edges with covalent bonds.Based on the density functional theory simulation,the electronic structure of the heterostructure,Li adsorption and Li diffusion on heterostructure were systematically investigated.Compared with the pristine BlueP,the existence of graphene layer increases the overall conductivity of BlueP-G intralayer heterostructure.The significantly enhanced adsorption energy indicates the Li deposition on anode surface is energetically favored.The fast diffusion of Li with energy barrier as low as 0.02-0.09 eV indicates the growth of Li dendrite could be suppressed and the stability and reversibility of the battery will be increased.With a combination of increased conductivity of electronic charge,excellent Li adsorption and Li mobility on surface,BlueP-G intralayer heterostructure with zigzag interface is quite promising in the application of anode material for Li-ion batteries.