Defect engineering in transition-metal(Fe,Co,andNi)-based electrocatalysts for water splitting

Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.Designing practical electrocatalysts by introducing defect engineering,such as hybrid structure,surface vacancies,functional modification,and structural distortions,is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities,robust stability,and good practicability.This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts.In detail,the types of defects,the preparation and characterization methods,and catalytic performances of electrocatalysts are presented,emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates'adsorption energy throughout the review.Finally,the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.An in-depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high-efficiency electrocatalysts for water splitting and other possible applications.

Professional Cognitive Education Model for Agricultural Water Conservancy Engineering under the Background of New Agricultural Science

The construction of new agricultural science requires the use of modern scientific and technological means to transform and enhance current agricultural related majors.The agricultural water conservancy engineering major,with its inherent disciplinary advantages,plays an indispensable and important role in the construction of new agricultural science.In recent years,the lack of professional cognitive education has gradually become a significant problem in the training of talents in agricultural water conservancy engineering.Therefore,this paper deeply analyzes the problems and reasons faced by professional cognitive education,and proposes specific educational strategies for several key aspects such as enrollment promotion,freshman enrollment education,construction of teacher team,combination of scientific research and teaching,and strengthening professional cognition through competition activities.It aims to provide reference for improving the quality of professional cognitive education and exploring effective ways.

Numerical analysis on water exchange and its response to the coastal engineering in the Yueqing Bay in China

On the basis of a numerical model of tidal current using Delft3D , the distribution of the semi-exchange time of water was simulated in the Yueqing Bay here. The result showed that the semi-exchange time was about more than 6 d in the bay end, and about 1~2 d in the bay mouth. Besides, based on the calculation of the semi-exchange time before and after the Xuanmen Dam project, a comparison between them was further carried out. And the same work was also done with the recent reclamation projects in the Yueqing Bay as well. The results showed that the change in semi-exchange time caused by the Xuanmen Dam project was about 6 d increase near the dam and 4.5 d increase at the bay end. And it was about 5 d increase at the bay end and 1 d increase at the mouth of the bay caused by the recent reclamation projects.

Interface Engineering of NixSy@MnOxHy Nanorods to Efficiently Enhance Overall-Water-Splitting Activity and Stability

Exploring highly active and stable transition metal-based bifunctional electrocatalysts has recently attracted extensive research interests for achieving high inherent activity, abundant exposed active sites, rapid mass transfer, and strong structure stability for overall water splitting. Herein, an interface engineering coupled with shell-protection strategy was applied to construct three-dimensional(3D) core-shell NixSy@MnOxHy heterostructure nanorods grown on nickel foam(NixSy@MnOxHy/NF) as a bifunctional electrocatalyst. NixSy@MnOxHy/NF was synthesized via a facile hydrothermal reaction followed by an electrodeposition process. The X-ray absorption fine structure spectra reveal that abundant Mn-S bonds connect the heterostructure interfaces of N ixSy@MnOxHy, leading to a strong electronic interaction, which improves the intrinsic activities of hydrogen evolution reaction and oxygen evolution reaction(OER). Besides, as an efficient protective shell, the MnOxHy dramatically inhibits the electrochemical corrosion of the electrocatalyst at high current densities, which remarkably enhances the stability at high potentials. Furthermore, the 3D nanorod structure not only exposes enriched active sites, but also accelerates the electrolyte diffusion and bubble desorption. Therefore, NixSy@MnOxHy/NF exhibits exceptional bifunctional activity and stability for overall water splitting, with low overpotentials of 326 and 356 mV for OER at 100 and 500 mA cm^(–2), respectively, along with high stability of 150 h at 100 mA cm^(–2). Furthermore, for overall water splitting, it presents a low cell voltage of 1.529 V at 10 mA cm^(–2), accompanied by excellent stability at 100 mA cm^(–2) for 100 h. This work sheds a light on exploring highly active and stable bifunctional electrocatalysts by the interface engineering coupled with shell-protection strategy.

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

Nowdays,electrocatalytic water splitting has been regarded as one of the most efficient means to approach the urgent energy crisis and environmental issues.However,to speed up the electrocatalytic conversion efficiency of their half reactions including hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),electrocatalysts are usually essential to reduce their kinetic energy barriers.Electrospun nanomaterials possess a unique one‐dimensional structure for outstanding electron and mass transportation,large specific surface area,and the possibilities of flexibility with the porous feature,which are good candidates as efficient electrocatalysts for water splitting.In this review,we focus on the recent research progress on the electrospun nanomaterials‐based electrocatalysts for HER,OER,and overall water splitting reaction.Specifically,the insights of the influence of the electronic modulation and interface engineering of these electrocatalysts on their electrocatalytic activities will be deeply discussed and highlighted.Furthermore,the challenges and development opportunities of the electrospun nanomaterials‐based electrocatalysts for water splitting are featured.Based on the achievements of the significantly enhanced performance from the electronic modulation and interface engineering of these electrocatalysts,full utilization of these materials for practical energy conversion is anticipated.

Catalyst Engineering for Electrochemical Energy Conversion from Water to Water:Water Electrolysis and the Hydrogen Fuel Cell

In the context of the current serious problems related to energy demand and climate change,substantial progress has been made in developing a sustainable energy system.Electrochemical hydrogen-water conversion is an ideal energy system that can produce fuels via sustainable,fossil-free pathways.However,the energy conversion efficiency of two functioning technologies in this energy system—namely,water electrolysis and the fuel cell—still has great scope for improvement.This review analyzes the energy dissipation of water electrolysis and the fuel cell in the hydrogen-water energy system and discusses the key barriers in the hydrogen-and oxygen-involving reactions that occur on the catalyst surface.By means of the scaling relations between reactive intermediates and their apparent catalytic performance,this article summarizes the frameworks of the catalytic activity trends,providing insights into the design of highly active electrocatalysts for the involved reactions.A series of structural engineering methodologies(including nano architecture,facet engineering,polymorph engineering,amorphization,defect engineering,element doping,interface engineering,and alloying)and their applications based on catalytic performance are then introduced,w让h an emphasis on the rational guidance from previous theoretical and experimental studies.The key scientific problems in the electrochemical hydrogen-water conversion system are outlined,and future directions are proposed for developing advanced catalysts for technologies with high energy-conversion efficiency.

Boosting overall saline water splitting by constructing a strain-engineered high-entropy electrocatalyst

High-entropy materials(HEMs),which are newly manufactured compounds that contain five or more metal cations,can be a platform with desired properties,including improved electrocatalytic performance owing to the inherent complexity.Here,a strain engineering methodology is proposed to design transition-metal-based HEM by Li manipulation(LiTM)with tunable lattice strain,thus tailoring the electronic structure and boosting electrocatalytic performance.As confirmed by the experiments and calculation results,tensile strain in the LiTM after Li manipulation can optimize the d-band center and increase the electrical conductivity.Accordingly,the asprepared LiTM-25 demonstrates optimized oxygen evolution reaction and hydrogen evolution reaction activity in alkaline saline water,requiring ultralow overpotentials of 265 and 42 mV at 10 mA cm−2,respectively.More strikingly,LiTM-25 retains 94.6%activity after 80 h of a durability test when assembled as an anion-exchange membrane water electrolyzer.Finally,in order to show the general efficacy of strain engineering,we incorporate Li into electrocatalysts with higher entropies as well.

Key techniques for evaluation of safety monitoring sensors in water conservancy and hydropower engineering

For the evaluation of construction quality and the verification of the design of water conservancy and hydropower engineering projects, and especially for the control of dam safety operation behavior, safety monitoring sensors are employed in a majority of engineering projects. These sensors are used to monitor the project during the dam construction and operation periods, and play an important role in reservoir safety operation and producing benefits. With the changing of operating environments and run-time of projects, there are some factors affecting the operation and management of projects, such as a certain amount of damaged sensors and instability of the measured data. Therefore, it is urgent to evaluate existing safety monitoring sensors in water conservancy and hydropower engineering projects. However, there are neither standards nor evaluation guidelines at present. Based on engineering practice, this study examined some key techniques for the evaluation of safety monitoring sensors, including the evaluation process of the safety monitoring system, on-site detection methods of two typical pieces of equipment, the differential resistor sensor and vibrating wire sensor, the on-site detection methods of communication cable faults, and a validity test of the sensor measured data. These key techniques were applied in the Xiaolangdi Water Control Project and Xiaoxi Hydropower Project. The results show that the measured data of a majority of sensors are reliable and reasonable, and can reasonably reflect the structural change behavior in the project operating process, indicating that the availabilities of the safety monitoring sensors of the two projects are high

Interface and M^(3+)/M^(2+)Valence Dual-Engineering on Nickel Cobalt Sulfoselenide/Black Phosphorus Heterostructure for Efficient Water Splitting Electrocatalysis

The catalyst innovation that aims at noble-metal-free substitutes is one key aspect for future sustainable hydrogen energy deployment.In this paper,a nickel cobalt sulfoselenide/black phosphorus heterostructure(NiCoSe|S/BP)was fabricated to realize the highly active and durable water electrolysis through interface and valence dual-engineering.The NiCoSe|S/BP nanostructure was constructed by in-situ growing NiCo hydroxide nanosheet arrays on few-layer BP and subsequently one-step sulfoselenization by SeS2.Besides the conductive merit of BP substrate,holes in p-type BP are capable of oxidizing the Co^(2+)to high-valence and electron-accepting Co^(3+),benefiting the oxygen evolution reaction(OER).Meanwhile,Ni^(3+)/Ni^(2+)ratio in the heterostructure is reduced to maintain the electrical neutrality,which corresponds to the increased electron-donating character for boosting hydrogen evolution reaction(HER).As for HER and OER,the heterostructured NiCoSe|S/BP electrocatalyst exhibits small overpotentials of 172 and 285 mV at 10 mA cm^(-2)(η_(10))in alkaline media,respectively.And overall water splitting has been achieved at a low cell potential of 1.67 V at η_(10) with high stability.Molecular sensing and density functional theory(DFT)calculations are further proposed for understanding the rate-determine steps and enhanced catalytic mechanism.The investigation presents a deep-seated perception for the electrocatalytic performance enhancement of BP-based heterostructure.

Solution chemistry back‐contact FTO/hematite interface engineering for efficient photocatalytic water oxidation

This work describes a simple yet powerful scalable solution chemistry strategy to create back‐contact rich interfaces between substrates such as commercial transparent conducting fluorine‐doped tin oxide coated glass(FTO)and photoactive thin films such as hematite for low‐cost water oxidation reaction.High‐resolution electron microscopy(SEM,TEM,STEM),atomic force microscopy(AFM),elemental chemical mapping(EELS,EDS)and photoelectrochemical(PEC)investigations reveal that the mechanical stress,lattice mismatch,electron energy barrier,and voids between FTO and hematite at the back‐contact interface as well as short‐circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions,thus increasing the overall efficiency of these low‐cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water‐splitting.These findings are of significant importance to improve the charge collection efficiency by minimizing electron‐hole recombination observed at back‐contact interfaces and grain boundaries in mesoporous electrodes,thus improving the overall efficiency and scalability of low‐cost PEC water splitting devices.

中国英文学术期刊品牌建设的路径思考--以Water Science and Engineering国际化实践为例

文章阐述了我国英文学术期刊品牌建设面临的挑战,并以英文刊Water Science and Engineering的品牌建设实践为例,分析了我国英文学术期刊品牌建设的有效路径。研究表明,英文学术期刊可以从找准定位和特色、控制学术质量、构建融媒体新生态环境、依靠专家资源以及坚持中国特色的国际合作等方面,加强期刊的品牌建设,建立期刊在国际学术和出版领域的影响力和权威性,从而为中国创办的英文学术期刊争取更多的国际话语权。

Interface engineering of porous Fe^(2)P-WO_(2.92) catalyst with oxygen vacancies for highly active and stable large-current oxygen evolution and overall water splitting

Constructing a low cost,and high-efficiency oxygen evolution reaction(OER)electrocatalyst is of great significance for improving the performance of alkaline electrolyzer,which is still suffering from highenergy consumption.Herein,we created a porous iron phosphide and tungsten oxide self-supporting electrocatalyst with oxygen-containing vacancies on foam nickel(Fe_(2)P-WO_(2.92)/NF)through a facile insitu growth,etching and phosphating strategies.The sequence-controllable strategy will not only generate oxygen vacancies and improve the charge transfer between Fe_(2)P and WO_(2.92) components,but also improve the catalyst porosity and expose more active sites.Electrochemical studies illustrate that the Fe_(2)P-WO_(2.92)/NF catalyst presents good OER activity with a low overpotential of 267 mV at 100 mA cm^(-2),a small Tafel slope of 46.3 mV dec^(-1),high electrical conductivity,and reliable stability at high current density(100 mA cm^(-2) for over 60 h in 1.0 M KOH solution).Most significantly,the operating cell voltage of Fe_(2)P-WO_(2.92)/NF‖Pt/C is as low as 1.90 V at 400 mA cm^(-2) in alkaline condition,which is one of the lowest reported in the literature.The electrocatalytic mechanism shows that the oxygen vacancies and the synergy between Fe_(2)P and WO_(2.92) can adjust the electronic structure and provide more reaction sites,thereby synergistically increasing OER activity.This work provides a feasible strategy to fabricate high-efficiency and stable non-noble metal OER electrocatalysts on the engineering interface.

Study on adverse effects of groundwater level rising induced by land creation engineering in hilly and gully area of the Loess Plateau

Land creation projects have been implemented in China to expand urban space in mountainous areas.In addition to the predictable settlement brought about by filling construction,varying degrees of land subsidence and engineering failures have a demonstrated relationship to groundwater level fluctuation induced by land creation engineering.In this work,we adopted a typical large-scale land creation project,Yan’an New City in Shaanxi province,West China,as our study area.Prior to conducting the main experiment,preliminary field investigation and groundwater level monitoring were conducted to determine the groundwater fluctuation trend induced by land creation engineering.Although a blind drainage system was implemented,the depth aspect of groundwater level changes after large-scale land creation still needed to be addressed.To study the degree of impact and the settlement mechanism induced by the rising groundwater level,we conducted a Water Immersion Test(WIT)in a typical land creation site for 107 days.The rising groundwater level was simulated by injecting water from the bottom of the filling foundation.During the WIT,the soil water content,surface subsidence,and internal settlement of soil at different depths were obtained.Surface subsidence development could be categorized into four stages during the water level increase.The second stage,which is defined as the point when the groundwater level rises to 10 m,marked the critical point in the process.Furthermore,it was ascertained that the local settlement in regions that were originally composed of steep slopes is larger than that in originally flat areas.In addition,ground cracks and sinkholes in the study area were inspected;and it was determined that they would become new channels that would accelerate water infiltration and exacerbate the settlement.Based on the results from our field investigation and testing,several suggestions are proposed for land creation projects to mitigate issues associated with construction-induced groundwater level rising.

Benefit measurement of the soil and water conservation for ecological forestry engineering

Data were collected from Three-north Region, Middle and upper reaches region of Yangtze River and Coastal region. By analysis of factors influencing soil erosion, the longitude, latitude, annual precipitation, and the slope degree were selected as regional independent variables and canopy density and stock litter were selected as independent variables, and integral diffusing models were established for evaluation of the benefit of soil and water conservation of forest. By solving the parameters of models using the package of STATISTICA, the Power function between independent variables and dependent variables was set up. The soil conservation amount of forest and economic values were estimated using the contrast method for the ecological forestry engineering of the above three areas.

Engineering the Local Coordination Environment of Single-Atom Catalysts and Their Applications in Photocatalytic Water Splitting:A Review

Single-atom catalysts(SACs),with atomically dispersed metal atoms anchored on a typical support,representing the utmost utilization effi ciency of the atoms,have recently emerged as promising catalysts for a variety of catalytic applications.The electronic properties of the active center of SACs are highly dependent on the local environment constituted by the single metal atom and its surrounding coordination elements.Therefore,engineering the coordination environment near single metal sites,from the fi rst coordination shell to the second shell or higher,would be a rational way to design effi cient SACs with optimized electronic structure for catalytic applications.The wide range of coordination confi gurations,guaranteed by the multiple choices of the type and heterogeneity of the coordination element(N,O,P,S,etc.),further off er a large opportunity to rationally design SACs for satisfactory activities and investigate the structure-performance relationship.In this review,the coordination engineering of SACs by varying the type of coordination element was elaborated and the photocatalytic water splitting of SACs was highlighted.Finally,challenging issues related to the coordination engineering of SACs and their photocatalytic applications were discussed to call for more eff orts devoted to the further development of single-atom catalysis.