Insight into the synergistic effect of defect and strong interface coupling on ZnIn_(2)S_(4)/CoIn_(2)S_(4)heterostructure for boosting photocatalytic H_(2) evolution

Steering the directional carrier migration across the interface is a central mission for efficient photocatalytic reactions.In this work,an atomic-shared heterointerface is constructed between the defect-rich ZnIn_(2)S_(4)(HVs-ZIS)and CoIn_(2)S_(4)(CIS)via a defect-guided heteroepitaxial growth strategy.The strong interface coupling induces adequate carriers exchanging passageway between HVs-ZIS and CIS,enhancing the internal electric field(IEF)in the ZnIn_(2)S_(4)/CoIn_(2)S_(4)(HVs-ZIS/CIS)heterostructure.The defect structure in HVs-ZIS induces an additional defect level,improving the separation efficiency of photocarriers.Moreover,promoted by the IEF and intimate heterointerface,photogenerated electrons trapped by the defect level can migrate to the valence band of CIS,contributing to massive photogenerated electrons with intense reducibility in HVs-ZIS/CIS.Consequently,the HVs-ZIS/CIS heterostructure performs a boosted H_(2)evolution activity of 33.65 mmol g^(-1)h^(-1).This work highlights the synergistic effects of defect and strong interface coupling in regulating carrier transfer and paves a brave avenue for constructing efficient heterostructure photocatalysts.

Defects and morphology engineering for constructing V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S nanotube heterojunction arrays toward efficient bifunctional electrocatalyst for overall water splitting

The development of highly active,stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great challenge.Herein,S vacancies-rich Ni_(3)S_(2)@Cu_(2)S nan-otube heterojunction arrays were in-situ grown on copper foam(V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF)for efficient electrocatalytic overall water splitting.With the merits of nanotube arrays and efficient electronic mod-ulation drived by the OD vacancy defect and 2D heterojunction defect,the resultant V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF electrocatalyst exhibits excellent electrocatalytic activity with a low overpotential of 47 mV for the hydrogen evolution reaction(HER)at 10 mA cm^(-2) current density,and 263 mV for the oxygen evolution reaction(OER)at 50 mA cm^(-2) current density,as well as a cell voltage of 1.48 V at 10 mA cm^(-2).Moreover,the nanotube heterojunction arrays endows V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF with outstanding stability in long-term catalytic processes,as confirmed by the continuous chronopotentiom-etry tests at current densities of 10 mA cm^(-2) for 100 h.

Effectively Modulating Oxygen Vacancies in Flower‑Likeδ‑MnO_(2)Nanostructures for Large Capacity and High‑Rate Zinc‑Ion Storage

In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.

Lithiation-induced controllable vacancy engineering for developing highly active Ni_(3)Se_(2) as a high-rate and large-capacity battery-type cathode in hybrid supercapacitors

The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni_(3)Se_(2)lamellas by pre-lithiation technique,which can be acted as a novel class of battery-type cathode for hybrid supercapacitors.Appropriately modulating the contents of the preembedded lithium(Li) ions can induce a controllable vacancy content in the series of as-prepared products,effectively endowing a fast reaction kinetic and high activity for the cathode.Benefiting from the distinct design,the optimized cathode(Li2-Ni_(3)Se_(2)) presents a high specific capacity of 236 mA h g^(-1)at1 A g^(-1),importantly,it can still possess 117 mA h g^(-1)when the current density is increased up to 100A g^(-1),exhibiting relatively high rate capability.It is much superior to other battery-type TMC cathodes reported in previous studies.Moreover,the cathode also shows the excellent cycling stability with 92%capacity retention after 3,000 cycles.In addition,a hybrid supercapacitor(HSC) is assembled with the obtained Li2-Ni_(3)Se_(2)as the cathode and active carbon(AC) as the anode,which delivers a high energy density of 77 W h kg^(-1)at 4 kW kg^(-1)and long-term durability(90% capacitance retention after 10,000 cycles).Therefore,the strategy not only provides an effective way to realize the controllable vacancy content in TMCs for achieving high-perfo rmance cathodes for HSC,but also further promotes their large-scale applications in the energy storage fields.

Enhancing Defect-Induced Dipole Polarization Strategy of SiC@MoO_(3)Nanocomposite Towards Electromagnetic Wave Absorption

Defect engineering in transition metal oxides semiconductors(TMOs)is attracting considerable interest due to its potential to enhance conductivity by intentionally introducing defects that modulate the electronic structures of the materials.However,achieving a comprehensive understanding of the relationship between micro-structures and electromagnetic wave absorption capabilities remains elusive,posing a substantial challenge to the advancement of TMOs absorbers.The current research describes a process for the deposition of a MoO_(3)layer onto SiC nanowires,achieved via electro-deposition followed by high-temperature calcination.Subsequently,intentional creation of oxygen vacancies within the MoO_(3)layer was carried out,facilitating the precise adjustment of electromagnetic properties to enhance the microwave absorption performance of the material.Remarkably,the SiC@MO-t4 sample exhibited an excellent minimum reflection loss of-50.49 dB at a matching thickness of 1.27 mm.Furthermore,the SiC@MO-t6 sample exhibited an effective absorption bandwidth of 8.72 GHz with a thickness of 2.81 mm,comprehensively covering the entire Ku band.These results not only highlight the pivotal role of defect engineering in the nuanced adjustment of electromagnetic properties but also provide valuable insight for the application of defect engineering methods in broadening the spectrum of electromagnetic wave absor ption effectiveness.SiC@MO-t samples with varying concentrations of oxygen vacancies were prepared through in-situ etching of the SiC@MoO_(3)nanocomposite.The presence of oxygen vacancies plays a crucial role in adjusting the band gap and local electron distribution,which in turn enhances conductivity loss and induced polarization loss capacity.This finding reveals a novel strategy for improving the absorption properties of electromagnetic waves through defect engineering.

Stable multi-electron reaction stimulated by W doping VS_(4)for enhancing magnesium storage performance

Rechargeable magnesium batteries(RMBs)hold promise for offering higher volumetric energy density and safety features,attracting increasing research interest as the next post lithium-ion batteries.Developing high performance cathode material by inducing multi-electron reaction process as well as maintaining structural stability is the key to the development and application of RMBs.Herein,multielectron reaction occurred in VS_(4)by simple W doping strategy.W doping induces valence of partial V as V^(2+)and V^(3+)in VS_(4)structure,and then stimulates electrochemical reaction involving multi-electrons in 0.5%W-V-S.The flower-like microsphere morphology as well as rich S vacancies is also modulated by W doping to neutralize structure change in such multi-electron reaction process.The fabricated 0.5%W-V-S delivers higher specific capacity(149.3 m A h g^(-1)at 50 m A g^(-1),which is 1.6 times higher than that of VS_(4)),superior rate capability(76 mA h g^(-1)at 1000 mA g^(-1)),and stable cycling performance(1500cycles with capacity retention ratio of 93.8%).Besides that,pesudocapaticance-like contribution analysis as well as galvanostatic intermittent titration technique(GITT)further confirms the enhanced Mg^(2+)storage kinetics during such multi-electron involved electrochemical reaction process.Such discovery provides new insights into the designing of multi-electron reaction process in cathode as well as neutralizing structural change during such reaction for realizing superior electrochemical performance in energy storage devices.

Atomic insights of electronic states engineering of GaN nanowires by Cu cation substitution for highly efficient lithium ion battery

Electronic engineering of gallium nitride(Ga N) is critical for enhancement of its electrode performance.In this work, copper(Cu) cation substituted Ga N(Cu-Ga N) nanowires were fabricated to understand the electronically engineered electrochemical performance for Li ion storage. Cu cation substitution was revealed at atomic level by combination of X-ray photoelectron spectroscopy(XPS), X-ray absorption fine structure(XAFS), density functional theory(DFT) simulation, and so forth. The Cu-Ga N electrode delivered high capacity of 813.2 m A h g^(-1) at 0.1 A g^(-1) after 200 cycles, increased by 66% relative to the unsubstituted Ga N electrode. After 2000 cycles at 10 A g^(-1),the reversible capacity was still maintained at326.7 m A h g^(-1). The DFT calculations revealed that Cu substitution introduced the impurity electronic states and efficient interatomic electron migration, which can enhance the charge transfer efficiency and reduce the Li ion adsorption energy on the Cu-Ga N electrode. The ex-situ SEM, TEM, HRTEM, and SAED analyses demonstrated the reversible intercalation Li ion storage mechanism and good structural stability. The concept of atomic-arrangement-assisted electronic engineering strategy is anticipated to open up opportunities for advanced energy storage applications.

English Sentence Recognition Based on HMM and Clustering

For English sentences with a large amount of feature data and complex pronunciation changes contrast to words, there are more problems existing in Hidden Markov Model (HMM), such as the computational complexity of the Viterbi algorithm and mixed Gaussian distribution probability. This article explores the segment-mean algorithm for dimensionality reduction of speech feature parameters, the clustering cross-grouping algorithm and the HMM grouping algorithm, which are proposed for the implementation of the speaker-independent English sentence recognition system based on HMM and clustering. The experimental result shows that, compared with the single HMM, it improves not only the recognition rate but also the recognition speed of the system.

表面富集的超小铂纳米颗粒耦合缺陷磷化钴用于高效的电催化水分解和柔性锌空气电池

开发多功能的纳米电催化剂可以提高单位催化剂表面活性密度.本课题组采用热解和还原工艺制备了具有多功能电催化性能的超小铂纳米颗粒耦合缺陷CoP的纳米材料(Pt/d-CoP/NPC),它具有较高的氧还原反应(ORR)半波电位(0.82 V).所合成的Pt/d-CoP/NPC电催化剂具有良好的电催化析氢反应活性,当反应活性达到10 mA cm^(-2)时,过电位分别为33 mV@1mol/L KOH, 10 mV@0.5 mol/L H_(2)SO_(4)和70 mV@1 mol/L PBS.Pt/d-CoP/NPC催化剂还表现出较好的析氧反应活性.以合成的催化剂Pt/d-CoP/NPC作为电极组装的全解水装置和可充电锌空气电池具有良好的活性和稳定性,可以持续有效地驱动全解水产氢,在存储可再生能源方面的具有较好的应用潜力.采用X射线光电子能谱(XPS)、拉曼光谱测试和傅里叶红外光谱测试(FTIR)等技术研究了Pt颗粒与CoP之间的相互作用,并利用密度泛函理论(DFT)计算研究了催化剂的ORR反应机制.Pt/d-CoP/NPC在129.3 (2p_(3/2))和130.1 eV (2p_(1/2))处的P 2p轨道观察到P-M键,证实了金属磷化物的存在.Pt/d-CoP/NPC的Co结合能相对于d-CoP/NPC的结合能发生了正移,表明Pt与CoP之间存在电子相互作用.由于Co和Pt的电负性差异,Pt/d-CoP/NPC中Pt的峰值与商用Pt/C相比呈负移,说明电子从Co向Pt转移.XPS也证实了碳的存在.此外,拉曼光谱也出现了碳的特征峰D峰和G峰.并且Pt/d-CoP/NPC和d-CoP/NPC的ID/IG值相似,说明Pt的引入不会影响碳基体的结构.在N 1s光谱中,检测到N-P和吡啶氮的存在,证实在Pt/d-CoP/NPC和d-CoP/NPC中形成了N, P掺杂的碳.此外, Pt/d-CoP/NPC的FTIR谱出现对应于P-O, N-P, C-C, C-H和O-H的峰,也证明了氮磷共掺杂碳的存在.通过DFT计算进一步分析Pt/d-CoP/NPC电催化剂具有良好ORR活性的原因.结果表明,电荷从CoP转移到Pt,有利于活性氧分子的活化,促进催化过程.对比不同模型ORR过程中间体的自由能图, Pt/d-CoP/NPC和Pt/C的速率决定步骤为O_(2)生成OOH^(*),合成的Pt/d-CoP/NPC具有有利的热力学过电位,证明了其高效的ORR性能.此外, Pt/d-CoP/NPC中Pt的d带中心相对于纯Pt有明显的正向费米能级转移,说明引入的CoP可以导致离域电子重分布,从而优化了反应中间体的吸附.综上,Pt/d-CoP/NPC催化剂中Pt与CoP之间存在相互作用,进而提高催化活性,该催化剂的合成有望为开发多功能电催化纳米材料提供参考.

Co-Ru alloy nanoparticles decorated onto two-dimensional nitrogen doped carbon nanosheets towards hydrogen/oxygen evolution reaction and oxygen reduction reaction

Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of renewable energy-related applications.Herein,Co-Ru based compounds supported on nitrogen doped two-dimensional(2D)carbon nanosheets(NCN)are developed via one step pyrolysis procedure(Co-Ru/NCN)for HER/ORR and following low-temperature oxidation process(Co-Ru@RuO_(x)/NCN)for OER.The specific 2D morphology guarantees abundant active sites exposure.Furthermore,the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance.Thus,the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER(70 mV at 10 mA cm^(-2))in 1 M KOH and ORR(half-wave potential E_(1/2)=0.81 V)in 0.1 M KOH.Especially,the Co-Ru@RuO_(x)/NCN obtained by oxidation exhibits splendid OER performance in both acid(230 mV at 10 mA cm^(-2))and alkaline media(270 mV at 10 mA cm^(-2))coupled with excellent stability.Consequently,the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments.This research provides a promising avenue for the advancement of multifunctional nanomaterials.

Multidimensional defects tailoring local electron and Mg^(2+) diffusion channels for boosting magnesium storage performance of WO_(3)/MoO_(2)

Defect engineering presents great promise in addressing lower specific capacity,sluggish diffusion kinetics and poor cycling life issues in energy storage devices.Herein,multidimensional(0D/2D/3D) structural defects are constructed in WO_(3)/MoO_(2) simultaneously via competing for and sharing with O atoms during simple hydrothermal process.OD and 2D defects tailor local electron,activating more sites and generating built-in electric fields to yield ion reservoir,meanwhile,3D defect owning lower anisotropic property tailors Mg^(2+) diffusion channels to fully exploit Mg^(2+) adsorbed sites induced by OD and 2D defects,enhance the kinetics and maintain structural stability.Benefitted from synergistic effect of 0D/2D/3D structural defects,the designed WO_(3)/MoO_(2) shows the higher specific capacity(112.8 mA h g^(-1) at 50 mA g^(-1) with average attenuation rate per cycle of 0.068%),superior rate capability and excellent cycling stability(specific capacity retention of 80% after 1500 cycles at 1000 mA g^(-1)).This strategy provides design ideas of introducing multidimensional structural defects for tailoring local electron and microstructure to improve energy storage property.

Valence state effect of Cu on photocatalytic CO_(2)reduction

Copper(Cu)is extensively employed in photocatalytic CO_(2)reduction reactions for the production of high-value products.The valence state of transition metals plays a pivotal role in influencing the catalytic process.However,due to the complex valence state changes of Cu in the CO_(2)reduction reaction,research on its valence state effect is lacking.The current work is to prepare a series of TiO_(2)/CuX with stable Cu valence composition using different copper halides(CuX and CuX_(2),X=Br or Cl)as precursors.The results show that the CuBr_(2)loading leads to Cu^(+)/Cu^(2+) mixed cocatalyst and exhibits the highest activity for CO_(2)photoreduction.The CH4 evolution rate of the TiO_(2)/CuBr_(2)catalyst is as high as 100.59μmol h^(-1)g^(-1),which is 6.6 times that of pristine TiO_(2).The CH4 selectivity reaches 77%.The enhanced catalytic activity and selectivity can be ascribed to the efficient surface adsorption,activation,excellent carrier separation,and transfer ofCu^(+)/Cu^(2+) mixed cocatalyst.Our findings provide a reference for designing highly active Cu-based photocatalysts.

Zwitterionic ring-opening polymerization of macrocyclic ethyleneoxy-substituted carbonate:Access to cyclic PEG-like polycarbonate

The innovation in polymer design to rival conventional polyethylene glycol(PEG)is an important approach to achieving a more sustainable society.Here,cyclic PEG-like polycarbonates having high molecular weight(4.4–49.5 kg/mol)were enabled through zwitterionic ring-opening polymerization(ZROP)of macrocyclic carbonates(MCs)mediated by N-heterocyclic carbene(NHC).The thermodynamic behavior of polymerization depends on the ring size of monomers.During this process,the ZROP of 11-membered MC was driven by the change of enthalpy(ΔH_(p))which differed from the ZROP of 14-membered MC driven by the entropic change(ΔS_(p)).Cyclic polycarbonates depicted improved thermostability(T_(d5%)≥204℃)and higher glass transition temperatures(T_(g)>–40℃)in comparison to their linear analogues(T_(d5%)≤185℃,T_(g)~–50℃).In addition,the mechanism of ZROP of MC was addressed through computational study.A distinct mechanism of polymerization distinguishable from the well-known NHC-mediated ZROP of cyclic esters was revealed,where the zwitterion from nucleophilic addition to MC,i.e.tetrahedral intermediate,cannot be ring-opened probably due to the delocalization of negative charge on the carbonate group,but serves as an active center for the polymerization.In comparison to PEG,the attained polymer demonstrated comparable hydrophilic and biocompatible properties,as revealed by the results of contact angle and in vitro cytotoxicity studies,suggesting that cyclic polycarbonate hold the promise as the alternative of PEG.

Hierarchical Fe_(x)Bi_(2−x)S_(3) solid solutions for boosted supercapacitor performance

For the pursuit of high energy supercapacitors,the development of high performance pseudocapacitance or battery-type negative electrode material is urgently needed to make up for the capacity shortage of commercial electric double layer capacitor(EDLC)type materials.Herein,a porous and defect-rich Fe_(x)Bi_(2-x)S_(3) solid solution structure is firstly constructed by employing Fe-doped Bi_(2)O_(2)CO_(3) porous nanosheets as a precursor,which presents dramatically increased energy storage performance than Bi_(2)S_(3) and FeS_(2) phase.For the optimized Fe_(x)Bi_(2-x)S_(3) solid solution(FeBiS-60%),the Fe solute is free and random dispersed in Bi_(2)S_(3) framework,which can effectively modulate the electronic structure of Bi element and introduce rich-defect due to the existence of Fe(II).Meanwhile,the FeBiS-60%,constructed by pore nanosheets that are assembled by self-supported basic nanorod units,presents rich mesoporous channels for fast mass transfer and abundant active sites for promoting capacity performance.Therefore,a high capacitance of 832.8 F·g^(-1) at a current density of 1 A·g^(-1) is achieved by the FeBiS-60%electrode.Furthermore,a fabricated Ni3S_(2)@Co_(3)S_(4)(NCS)//FeBiS-60%hybrid supercapacitor device delivers an outstanding energy density of 85.33 Wh·kg^(-1) at the power density of 0.799 kW·kg^(-1),and ultra-long lifespan of remaining 86.7%initial capacitance after 8700 cycles.

Graphdiyne scaffold anchored highly dispersed ruthenium nanoparticles as an efficient cathode catalyst for rechargeable Li-CO_(2) battery

Lithium (Li)-CO_(2) battery is rising as an attractive energy-storage system with the competence of CO_(2) conversion/fixation. However, its practical development is seriously hindered by the high overpotential. Herein, a rational design on a highly catalytic Li-CO_(2) battery electrode built by graphdiyne powder as a multi-functional laminar scaffold with anchored highly dispersed Ru nanoparticles is explored. The strong interaction between the abundant acetylenic bond sites of graphdiyne scaffold and Ru nanoparticles can effectively promote the electrochemical progress and reduce the voltage polarization. The unique channels architecture of the cathodic catalyst with enough space not only accelerates CO_(2) diffusion and electrons/Li+ transport, but also allows a large amount of accommodation for discharged product (Li2CO3) to assure an advanced capacity. The corresponding Li-CO_(2) battery displays an advanced discharged capacity of 15,030 mAh/g at 500 mA/g, great capacity retention of 8873 mAh/g at 2 A/g, high coulombic efficiency of 97.6% at 500 mA/g and superior life span for 120 cycles with voltage gap of 1.67 V under a restricted capacity of 1000 mAh/g at 500 mA/g. Ex/in-situ studies prove that synergy between Ru nanoparticles and acetylene bonds of GDY can boost the round-trip CO_(2)RR and CO_(2)ER kinetics.

An Equivalent Substitute Strategy for Constructing 3D Ordered Porous Carbon Foams and Their Electromagnetic Attenuation Mechanism

Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,and the specific attenuation mechanism is still ambiguous.Therefore,in this work,a novel ultra-light egg-derived porous carbon foam(EDCF)structure has been successfully constructed by a simple carbonization combined with the silica microsphere template-etching process.Based on an equivalent substitute strategy,the influence of pore volume and specific surface area on the electromagnetic parameters and EMW absorption properties of the EDCF products was confirmed respectively by adjusting the addition content and diameter of silica microspheres.As a primary attenuation mode,the dielectric loss originates from the comprehensive effect of conduction loss and polarization loss in S-band and C band,and the value is dominated by polarization loss in X band and Ku band,which is obviously greater than that of conduction loss.Furthermore,in all samples,the largest effective absorption bandwidth of EDCF-3 is 7.12 GHz under the thickness of 2.13 mm with the filling content of approximately 5 wt%,covering the whole Ku band.Meanwhile,the EDCF-7 sample with optimized pore volume and specific surface area achieves minimum reflection loss(RL_(min))of−58.08 dB at 16.86 GHz while the thickness is 1.27 mm.The outstanding research results not only provide a novel insight into enhancement of EMW absorption properties but also clarify the dominant dissipation mechanism for the porous carbon-based absorber from the perspective of objective experiments.

Controllable oxygen vacancies and morphology engineering:Ultra-high HER/OER activity under base–acid conditions and outstanding antibacterial properties

Introducing vacancy defects and unique morphology is an effective strategy to improve the catalytic performance of transition metal compounds.However,precisely controlling the amount of vacancy defects remains challenging.Here,we propose a facile and efficient hydrothermal accompanying an annealing method to synthesize a series of Mn-doped CoO nanomaterials with controllable oxygen vacancies and unique morphology.The oxygen vacancies amount can be precisely controlled by adjusting the Mndoping content and is positively correlated with catalytic performance.It was found that the oxygen vacancies amount can reach up to 38.2%over the Mn-doped CoO nanomaterials,resulting in ultra-high hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalytic activity(HER:25.6 and 37 m V at 10 m A cm^(-2);OER:301 and 322 m V at 50 m A cm^(-2))under both basic and acidic conditions,while reaching 10 m A cm^(-2) for an ultra-low cell voltage of only 1.52 V,which exceeds that of Pt/C/RuO_(2) and all reported non-noble metal oxide catalysts.The DFT calculations reveal oxygen vacancies can optimize H*and HOO*intermediates adsorption free energy,thus improving the HER and OER performance.Interestingly,the Mn-doped CoO with rich oxygen vacancies exhibits excellent antibacterial properties in vitro of biomedicine.This work provides new ideas and methods for the rational design and precise control of vacancy defects in transition metal compounds and explores their potential application value in electrochemical water splitting and biomedical fields.

Pt-surface oxygen vacancies coupling accelerated photo-charge extraction and activated hydrogen evolution

Semiconductors-based heterogeneous photocatalytic water splitting has been extensively studied,but it still remains challenging to accelerate the separation of electron-hole pairs and facilitate the reaction kinetics.Here we report a general strategy to fabricate highly efficient Pt/TiO_(2)photocatalyst by coupling the Pt co-catalysts and surface oxygen vacancies(VO)of TiO_(2).TiO_(2)was pre-modified with alkali or alkaline earth metals ion solutions,which produce a large number of surface hydroxyl on TiO_(2).Subsequently,the photodeposited Pt sub-nanoparticles substitute surface hydroxyl and induce surface VO on TiO_(2).The coupling of Pt and surface VO on TiO_(2)can accelerate the extraction of photo-charges through the interaction of Pt-VO-Ti bonds and reduce the hydrogen evolution barrier,thereby promoting the photocatalytic activity.The synthesized Pt-VO-TiO_(2)sample exhibits a photocatalytic hydrogen evolution activity as high as 1.5 L·g^(−1)·h^(−1),which is 2.2 times that of traditional Pt/TiO_(2).Our findings indepth understand the synergistic effect of co-catalysts and defects on photocatalysis and open up new possibilities for achieving robust photocatalytic water splitting.

Porous needle-like Fe-Ni-P doped with Ru as efficient electrocatalyst for hydrogen generation powered by sustainable energies

Electrocatalytic water electrolysis,involving hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),two halfreactions,is an eco-friendly approach toward hydrogen production.In this work,needle-like Ru-Fe-Ni-P on NiFe foam is prepared through corrosive engineering and following a low-temperature phosphorization procedure for overall water-splitting.The as-designed Ru-Fe-Ni-P exhibits a porous needle-like structure,surface,and binder-free merits,and then can expose rich active sites,favor the transportation of mass/electron,and accelerate the reaction kinetics during catalytic process.Then,the synthesized Ru-Fe-Ni-P owns remarkable catalytic performance for HER,with 18 and 67 mV to reach 10 mA·cm^(−2)in alkaline and neutral media.Moreover,a low cell voltage of 1.51 V is required to produce a current of 10 mA·cm^(−2)in a two electrode electrolyzer with excellent stability.Interestingly,sustainable energies can power the electrolyzer effectively with abundant hydrogen generation.

High area-capacity Mg batteries enabled by sulfur/copper integrated cathode design

Rechargeable Mg batteries potentially display lower cost and competitive energy density compared with their Li-ion counterparts.However,the practical implementation of high area-capacity cathodes still remains a formidably challenging task.This work presents the sulfur/copper integrated cathodes fabricated by the conventional blade-coating process and slurry-dipping method.The sulfur/copper foil integrated cathodes deliver a high area-capacity of 2.6 mAh cm^(-2)after 40 cycles,while the sulfur/copperfoam integrated cathode exhibits an ultrahigh area-capacity of 35.4 mAh cm^(-2),corresponding to 743.1 Wh L^(-1)at the electrode level(1.5 times higher than the LiCoO_(2)-graphite system).The in-situ formed copper sulfide intermediates with sufficient cation defects can act as functional intermediates to regulate the sulfur electrochemistry during the first discharge process.The subsequent cycles are operated by the reversible displacement reaction between Mg-ions and copper sulfide active substances.In particular,the copper ions prefer to extrude along the[001]direction in copper sulfides lattice and simultaneously the rock-salt MgS crystals are generated.Besides,the nonuniform surface topography of the cycled Mgmetal anode,caused by the spatial inhomogeneity in current distribution,is demonstrated to lead to the battery performance degradation for high area-capacity Mg batteries.