Three‐dimensional(3D)‐printed MXene high‐voltage aqueous micro‐supercapacitors with ultrahigh areal energy density and low‐temperature tolerance

The rapid advancement in the miniaturization,integration,and intelligence of electronic devices has escalated the demand for customizable microsupercapacitors(MSCs)with high energy density.However,efficient microfabrication of safe and high‐energy MXene MSCs for integrating microelectronics remains a significant challenge due to the low voltage window in aqueous electrolytes(typically≤0.6 V)and limited areal mass loading of MXene microelectrodes.Here,we tackle these challenges by developing a highconcentration(18mol kg^(−1))“water‐in‐LiBr”(WiB)gel electrolyte for MXene symmetric MSCs(M‐SMSCs),demonstrating a record high voltage window of 1.8 V.Subsequently,additive‐free aqueous MXene ink with excellent rheological behavior is developed for three‐dimensional(3D)printing customizable all‐MXene microelectrodes on various substrates.Leveraging the synergy of a highvoltage WiB gel electrolyte and 3D‐printed microelectrodes,quasi‐solid‐state MSMSCs operating stably at 1.8 V are constructed,and achieve an ultrahigh areal energy density of 1772μWhcm^(−2) and excellent low‐temperature tolerance,with a long‐term operation at−40℃.Finally,by extending the 3D printing protocol,M‐SMSCs are integrated with humidity sensors on a single planar substrate,demonstrating their reliability in miniaturized integrated microsystems.

Ink formulation, scalable applications and challenging perspectives of screen printing for emerging printed microelectronics

Screen printing is regarded as a highly competitive manufacture technology for scalable and fast fabrication of printed microelectronics, owing to its advanced merits of low-cost, facile operability and scalability.However, its large-scale application in printed microelectronics is still limited by screen printing functional ink. In this review, we summarize the recent advances of ink formation, typical scalable applications, and challenging perspectives of screen printing for emerging printed microelectronics. Firstly, we introduce the major mechanism of screen printing and the formation of different organic-and aqueous-based inks by various solvents and binders. Next, we review the most widely used applications of screen printing technique in micro-batteries, micro-supercapacitors and micro-sensors, demonstrative of wide applicability.Finally, the perspectives and future challenges in the sight of screen printing are briefly discussed.

Mechanism of calcium lignosulfonate in apatite and dolomite flotation system

Since the physical and chemical properties of apatite and dolomite can be similar,the separation of these two minerals is difficult.Therefore,when performing this separation using the flotation method,it is necessary to search for selective depressants.An experimental research was performed on the separation behavior of apatite and dolomite using calcium lignosulfonate as a depressant,and the mechanism by which this occurs was analyzed.The results show that calcium lignosulfonate has a depressant effect on both apatite and dolomite,but the depressant effect on dolomite is stronger at the same dosage.Mechanism analysis shows that the adsorptive capacity of calcium lignosulfonate on dolomite is higher than that of apatite,which is due to the strong reaction between calcium lignosulfonate and the Ca sites on dolomite.In addition,there is a hydrogen bond between calcium lignosulfonate and dolomite,which further prevents the adsorption of sodium oleate to dolomite,thus greatly inhibiting the flotation of dolomite.

Two-dimensional Boron Nitride for Electronics and Energy Applications

Two-dimensional(2D)boron nitride(BN),the so-called“white graphene,”has demonstrated a great potential in various fields,particularly in electronics and energy,by utilizing its wide bandgap(~5.5 eV),superior thermal stability,high thermal conductance,chemical inertness,and outstanding dielectric properties.However,to further optimize the performances from the view of structure-property relationship,the determinative factors such as crystallite sizes,layer thickness,dispersibility,and surface functionalities should be precisely controlled and adjusted.Therefore,in this review,the synthesis and functionalization methods including“top-down”and“bottom-up”strategies,and non-covalent and covalent modifications for 2D BN are systematically classified and discussed at first,thus catering for the requirements of versatile applications.Then,the progresses of 2D BN applied in the fields of microelectronics such as fieldeffect transistors and dielectric capacitors,energy domains such as thermal energy management and conversion,and batteries and supercapacitors are summarized to highlight the importance of 2D BN.Notably,these contents not only contain the state-of-the-art 2D BN composites,but also bring the current novel design of 2D BN-based microelectronic units.Finally,the challenges and perspectives are proposed to better broaden the scope of this material.Therefore,this review will pave an all-around way for understanding,utilizing,and applying 2D BN in future electronics and energy applications.

Sustainable Lignin-Derived Carbon as Capacity-Kinetics Matched Cathode and Anode towards 4.5 V High-Performance Lithium-Ion Capacitors

The Li-ion capacitors(LICs)develop rapidly due to their double-high features of high-energy density and high-power density.However,the relative low capacity of cathode and sluggish kinetics of anode seriously impede the development of LICs.Herein,the precisely pore-engineered and heteroatomtailored defective hierarchical porous carbons(DHPCs)as large-capacity cathode and high-rate anode to construct high-performance dual-carbon LICs have been developed.The DHPCs are prepared based on triple-activation mechanisms by direct pyrolysis of sustainable lignin with urea to generate the interconnected hierarchical porous structure and plentiful heteroatominduced defects.Benefiting from these advanced merits,DHPCs show the well-matched high capacity and fast kinetics of both cathode and anode,exhibiting large capacities,superior rate capability and long-term lifespan.Both experimental and computational results demonstrate the strong synergistic effect of pore and dopants for Li storage.Consequently,the assembled dual-carbon LIC exhibits high voltage of 4.5 V,high-energy density of 208 Wh kg^(−1),ultrahigh power density of 53.4 kW kg^(−1)and almost zerodecrement cycling lifetime.Impressively,the full device with high mass loading of 9.4 mg cm^(−2)on cathode still outputs high-energy density of 187 Wh kg^(−1),demonstrative of their potential as electrode materials for high-performance electrochemical devices.

活化高熵氧化物中部分金属位点显著增强热催化和电催化

高熵氧化物(HEOs)作为一种新兴材料受到科研工作者的广泛关注,并推动了高熵陶瓷材料(碳化物、硫化物、氟化物等)的发展及其在介电、磁学、储氢以及能源转化等领域中的应用.其中,HEOs由于丰富的活性位点、可调节的比表面积、稳定的晶体结构、独特的几何相容性和电子结构等特性在催化化学领域展示出广阔的应用前景.然而,受制于HEOs的结构特点和难以精确调控的物化性质,当前的研究主要围绕HEOs制备方法的探索及其在不同催化反应中的尝试.在以HEOs为基体进行的催化反应中,也有将贵金属与HEOs复合进行催化剂制备和催化应用的研究报道,但效果并不理想.因此,如何直接对HEOs进行改性并提升其催化性能是低成本高效促进HEOs在催化领域发展的重要途径.本文首先采用固相燃烧法制备CuCoNiZnAl HEOs,同时在制备过程中加入硫脲后通过焙烧处理来进行物化性质的原位调节(记为CuCoNiZnAl-T),随后采用碱液对CuCoNiZnAl-T处理来实现形貌的改变和物化性质的进一步优化(记为CuCoNiZnAl-T-NaOH).X射线粉末衍射结果表明,硫脲添加和碱处理未改变CuCoNiZnAl-T-NaOH的晶型结构.电镜结果表明,CuCoNiZnAl和CuCoNiZnAl-T均呈现出较大的颗粒状,而CuCoNiZnAl-T-NaOH具有大片层形貌结构和明显的晶格扭曲.此外,H_(2)程序升温还原、X射线光电子能谱和He程序升温脱附结果表明,CuCoNiZnAl-T-NaOH不仅具有容易还原的铜、镍、钴的氧化物物种,而且具有高含量和更活泼的晶格氧物种.因此,CuCoNiZnAl-T-NaOH在活性测试中展示出较好的CO_(2)加氢和CO氧化催化性能.其中CuCoNiZnAl-T-NaOH在催化CO氧化反应中,当转化率达到50%时所需转化温度为176℃,比相同条件下CuCoNiZnAl和CuCoNiZnAl-T作为催化剂达到同样催化效果时所需转化温度分别低36和21℃.此外,当CuCoNiZnAl-T-NaOH用作锂氧电池电极材料时也展示出较好的电催化活性(放电/充电容量为12049/9901 mAh/g)和循环稳定性(2500 h).随后,以CO_(2)加氢反应为研究对象,进一步采用近常压X射线光电子能谱进行反应机理分析,结果表明,相对于CuCoNiZnAl而言,CuCoNiZnAl-T在CO_(2)加氢反应过程中表面镍和钴的氧化物物种与活化的晶格氧之间更容易进行电子转移,这种增强的电子传输能力和更强的CO_(2)吸附能力有利于CO_(2)加氢反应的进行.推断这种电子传输能力的提升同样有利于CO氧化和锂氧电池性能的提升.综上,本文为HEOs催化剂的简洁制备和物化性质改善提供了技术借鉴,有望进一步推进HEOs的改性制备和在其他领域的功能化应用发展.

Low-temperature and high-voltage planar micro-supercapacitors based on anti-freezing hybrid gel electrolyte

Micro-supercapacitors(MSCs)are considered as highly competitive power sources for miniaturized electronics.However,narrow voltage window and poor anti-freezing properties of MSCs in conventional aqueous electrolytes lead to low energy density and limited environmental adaption.Herein,we report the construction of low-temperature and high-energy-density MSCs based on anti-freezing hybrid gel electrolytes(HGE)through introducing ethylene glycol(EG)additives into aqueous LiCl electrolyte.Since EG partially destroys hydrogen bond network among water molecules,the HGE exhibits maximum electrochemical stability window of 2.7 V and superior anti-freezing features with a glass transition temperature of-62.8℃.Further,the optimized MSCs using activated carbon microelectrodes possess impressive volumetric capacitance of 28.9 F cm^(-3)and energy density of 10.3 mWh cm^(-3)in the voltage of 1.6 V,2.6 times higher than MSCs tested in 1.2 V.Importantly,the MSCs display 68.3%capacitance retention even at-30℃ compared to the value at 25℃,and ultra-long cyclability with 85.7%of initial capacitance after 15,000 times,indicating extraordinary low-temperature performance.Besides,our devices offer favorable flexibility and modular integration.Therefore,this work provides a general strategy of realizing flexible,safe and anti-freezing microscale power sources,holding great potential towards subzero-temperature microelectronic applications.

Interfacial assembly of 2D polydopamine/graphene heterostructures with well-defined mesopore and tunable thickness for high-energy planar micro-supercapacitors

Two-dimensional(2D)mesoporous pseudocapacitive polymer/graphene heterostructures combine the advanced merits of 2D materials and mesoporous materials,possessing unique nanosheet structure,large specific surface area(SSA),abundant oxygen/nitrogen-containing groups,desirable electrical conductivity and admirable electrochemical redox activity,and hold great potential for constructing high-performance planar micro-supercapacitors(MSCs).Herein,we demonstrate the interfacial assembly of 2D mesoporous polydopamine/graphene(mPDG)heterostructures with well-defined mesopore structure(12 nm)and adjustable thickness(7.5–14.1 nm)for planar high-energy pseudocapacitive MSCs.Attributed to medium thickness,exposed mesopore of 12 nm and large SSA of 108 m^(2)/g,the m PDG with 10.8 nm thickness reveals prominent mass capacitance of 419 F/g and impressive cycling stability with~96%capacitance retention after 5000 cycles.Furthermore,the symmetric mPDG-based MSCs with“water-in-salt”gel electrolyte present wide voltage window of 1.6 V,superior volumetric energy density of 11.5 mWh/cm^(3),outstanding flexibility and self-integration ability.Therefore,this work offers a new platform of controllably synthesizing 2D mesoporous heterostructures for high-performance MSCs.

MXene coupled with molybdenum dioxide nanoparticles as 2D-0D pseudocapacitive electrode for high performance flexible asymmetric micro-supercapacitors

Recently,two-dimensional(2D)transition metal carbides and carbonitrides(MXenes),have shown great potential in micro-supercapacitors(MSCs).However,the maximum voltage output of symmetric MXene MSCs is limited to 0.6 V due to the oxidation effects at high anodic potentials.Herein,we developed asymmetric micro-supercapacitors(AMSCs)based on titanium carbide MXene(Ti_(3)C_(2)Tx)and MXene-MoO_(2) electrodes with an enlarged voltage window of 1.2 V,which is twice wider than that of symmetric MXene MSCs.The 2D-0D MXene-MoO_(2) microelectrode is fabricated by homogenous dispersing zerodimensional(0D)MoO_(2) nanoparticles into MXene layers to impede layers stacking and MoO_(2) nanoparticles aggregation.Notably,the AMSCs delivered good electrochemical performances of areal capacitance of ~19 mF cm^(-2) and volumetric capacitance of 63 F cm^(-3) at a scan rate of 2 mV s^(-1),and high energy density of 9.7 mW h cm^(-3) at a power density of 0.198 W cm^(-3).The AMSCs also presented exceptionally mechanical flexibility under different bending states and excellent cyclic stability,with 88% capacitance retention after 10000 cycles at a discharge current density of 0.5 mA cm^(-2).For practical application,the serially connected AMSCs are fully affordable to power electronics,which is beneficial for soft and wearable power devices.

Two‑Dimensional Mesoporous Materials for Energy Storage and Conversion:Current Status,Chemical Synthesis and Challenging Perspectives

Two-dimensional(2D)mesoporous materials(2DMMs),defined as 2D nanosheets with randomly dispersed or orderly aligned mesopores of 2–50 nm,can synergistically combine the fascinating merits of 2D materials and mesoporous mate-rials,while overcoming their intrinsic shortcomings,e.g.,easy self-stacking of 2D materials and long ion transport paths in bulk mesoporous materials.These unique features enable fast ion diffusion,large specific surface area,and enriched adsorption/reaction sites,thus offering a promising solution for designing high-performance electrode/catalyst materials for next-generation energy storage and conversion devices(ESCDs).Herein,we review recent advances of state-of-the-art 2DMMs for high-efficiency ESCDs,focusing on two different configurations of in-plane mesoporous nanosheets and sandwich-like mesoporous heterostructures.Firstly,a brief introduction is given to highlighting the structural advantages(e.g.,tailored chemical composition,sheet configuration,and mesopore geometry)and key roles(e.g.,active materials and functional additives)of 2DMMs for high-performance ESCDs.Secondly,the chemical synthesis strategies of 2DMMs are summarized,including template-free,2D-template,mesopore-template,and 2D mesopore dual-template methods.Thirdly,the wide applications of 2DMMs in advanced supercapacitors,rechargeable batteries,and electrocatalysis are discussed,enlightening their intrinsic structure–property relationships.Finally,the future challenges and perspectives of 2DMMs in energy-related fields are presented.