Templated synthesis of transition metal phosphide electrocatalysts for oxygen and hydrogen evolution reactions

Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.

Recent advances in transition metal phosphide materials:Synthesis and applications in supercapacitors

Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors.As the battery-type materials,transition metal phosphides(TMPs)possess high theoretical specific capacity,good electrical conductivity and superior structural stability,which have been extensively studied to be electrode materials for supercapacitors.In this review,we summarize the up-to-date progress on TMPs materials from diversified synthetic methods,diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors.In the end,we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.

Metal-organic frameworks derived transition metal phosphides for electrocatalytic water splitting

It is critical to synthesize high-efficiency electrocatalysts to boost the performance of water splitting to meet the requirements of industrial applications. Metal-organic frameworks(MOFs) can function as ideal molecular platforms for the design of highly reactive transition metal phosphides(TMPs), a kind of candidates for high-efficiently electrocatalytic water splitting. The intrinsic activity of the electrocatalysts can be greatly improved via modulating the electronic structure of the catalytic center through the MOF precursors/templates. Moreover, the carbon layer converted in-situ by the organic ligands can not only protect the TMPs from being degraded in the harsh electrochemical environments, but also avoid agglomeration of the catalysts, thereby promoting their activities and stabilities. Furthermore,heteroatom-containing ligands can incorporate N, S or P, etc. atoms into the carbon matrixes after conversion, regulating the coordination microenvironments of the active centers as well as their electronic structures. In this review, we first summarized the latest developments in MOF-derived TMPs by the unique advantages in metal, organic ligand, and morphology regulations for electrocatalytic water splitting. Secondly, we concluded the critical scientific issues currently facing for designing state-of-the-art TMP-based electrocatalysts. Finally, we presented an outlook on this research area, encompassing electrocatalyst construction, catalytic mechanism research, etc.

Thioetherification of isoprene and butanethiol on transition metal phosphides

Thioetherification between mercaptan and diolefin is an efficient process to remove mercaptans in FCC gasoline at mild condition, during which the selective hydrogenation of diolefin to monoolefin is also expected. Here, Si O2 supported transition metal（Fe, Co, Ni, Mo and W） phosphides were tested for the thioetherification of isoprene and butanethiol on a fixed-bed reactor at 120℃ and 1.5 MPa H2, and their structure before and after reaction was characterized by means of XRD, HRTEM, N2 sorption, CO chemisorption, NH3-TPD, XPS and TG. It was found that, among different metal phosphides, Mo P/Si O2 showed the best performance, and the optimal nominal Mo P loading was 25%. Apart from the nature of metal, the density of metal and acid sites determined the catalyst performance. Metal site was mainly responsible for hydrogenation of isoprene, while acid site dominantly contributed to the thioetherification and the polymerization of olefins. Moreover, a balance between metallic and acidic functions is required to arrive at a desired performance. Excessive metal sites or acid sites led to the over-hydrogenation of isoprene or the severe polymerization of olefins, respectively. 25%Mo P/Si O2 was tested for 37 h time on stream, and butanethiol conversion maintained at 100%; although isoprene conversion remarkably decreased, the selectivity to isopentenes exceeded 80% after reaction for 11 h. We suggest that the deactivation of Mo P/Si O2 is mainly ascribed to the butanethiol poisoning and the carbonaceous deposit, especially the former.

Activating Ru in the pyramidal sites of Ru_(2)P-type structures with earth-abundant transition metals for achieving extremely high HER activity while minimizing noble metal content

Rational design of efficient pH-universal hydrogen evolution reaction catalysts to enable large-scale hydrogen production via electrochemical water splitting is of great significance,yet a challenging task.Herein,Ru atoms in the Ru_(2)P structure were replaced with M=Co,Ni,or Mo to produce M_(2-x)Ru_(x)P nanocrystals.The metals show strong site preference,with Co and Ni occupying the tetrahedral sites and Ru the square pyramidal sites of the CoRuP and NiRuP Ru_(2)P-type structures.The presence of Co or Ni in the tetrahedral sites leads to charge redistribution for Ru and,according to density functional theory calculations,a significant increase in the Ru d-band centers.As a result,the intrinsic activity of CoRuP and NiRuP increases considerably compared to Ru_(2)P in both acidic and alkaline media.The effect is not observed for MoRuP,in which Mo prefers to occupy the pyramidal sites.In particular,CoRuP shows state-of-the-art activity,outperforming Ru_(2)P with Pt-like activity in 0.5 M H_(2)SO_(4)(η_(10)=12.3 mV;η100=52 mV;turnover frequency(TOF)=4.7 s^(-1)).It remains extraordinarily active in alkaline conditions(η10=12.9 mV;η_(100)=43.5 mV)with a TOF of 4.5 s^(-1),which is 4x higher than that of Ru_(2)P and 10x that of Pt/C.Further increase in the Co content does not lead to drastic loss of activity,especially in alkaline medium,where,for example,the TOF of Co_(1.9)Ru_(0.1)P remains comparable to that of Ru_(2)P and higher than that of Pt/C,highlighting the viability of the adopted approach to prepare cost-efficient catalysts.

Multicomponent transition metal phosphide for oxygen evolution

Transition metal phosphides(TMPs)have exhibited decent performance in an oxygen evolution reaction(OER),which is a kinetic bottleneck in many energy storages and conversion systems.Most reported catalysts are composed of three or fewer metallic components.The inherent complexity of multicomponent TMPs with more than four metallic components hinders their investigation in rationally designing the structure and,more importantly,comprehending the component-activity correlation.Through hydrothermal growth and subsequent phosphor-ization,we reported a facile strategy for combining TMPs with tunable elemental compositions(Ni,Fe,Mn,Co,Cu)on a two-dimensional ti-tanium carbide(MXene)flake.The obtained TMPs/MXene hybrid nanostructures demonstrate homogeneously distributed elements.They ex-hibit high electrical conductivity and strong interfacial interaction,resulting in an accelerated reaction kinetics and long-term stability.The res-ults of different component catalysts’OER performance show that NiFeMnCoP/MXene is the most active catalyst,with a low overpotential of 240 mV at 10 mA·cm−2,a small Tafel slope of 41.43 mV·dec−1,and a robust long-term electrochemical stability.According to the electrocata-lytic mechanism investigation,the enhanced NiFeMnCoP/MXene OER performance is due to the strong synergistic effect of the multi-ele-mental composition.Our work,therefore,provides a scalable synthesis route for multi-elemental TMPs and a valuable guideline for efficient MXene-supported catalysts design.

Heterostructured bimetallic phosphide nanowire arrays with latticetorsion interfaces for efficient overall water splitting

Designing cost-effective and high-efficiency electrocatalysts is critical to the water splitting performance during hydrogen generation.Herein,we have developed Fe_(2)P-Co_(2)P heterostructure nanowire arrays with excellent lattice torsions and grain boundaries for highly efficient water splitting.According to the microstructural investigations and theoretical calculations,the lattice torsion interface not only contributes to the exposure of more active sites but also effectively tunes the adsorption energy of hydrogen/oxygen intermediates via the accumulation of charge redistribution.As a result,the Fe_(2)P-Co_(2)P heterostructure nanowire array exhibits exceptional bifunctional catalytic activity with overpotentials of 65 and 198 mV at 10 mA cm^(-2) for hydrogen and oxygen evolution reactions,respectively.Moreover,the Fe_(2)P-Co_(2)P/NF-assembled electrolyzer can deliver 10 mA cm^(-2) at an ultralow voltage of1.51 V while resulting in a high solar-to-hydrogen conversion efficiency of 19.8%in the solar-driven water electrolysis cell.

Atomic orbitals modulated dual functional bimetallic phosphides derived from MOF on MOF structure for boosting high efficient overall water splitting

The electronic modulation characteristics of efficient metal phosphide electrocatalysts can be utilized to tune the performance of oxygen evolution reaction(OER).However,improving the overall water splitting performance remains a challenging task.By building metal organic framework(MOF)on MOF heterostructures,an efficient strategy for controlling the electrical structure of MOFs was presented in this study.ZIF-67 was in-situ synthesized on MIL-88(Fe)using a two-step self-assembly method,followed by low-temperature phosphorization to ultimately synthesize FeP-CoP_(3)bimetallic phosphides.By combining atomic orbital theory and theoretical calculations(density functional theory),the results reveal the successful modulation of electronic orbitals in FeP-CoP_(3)bimetallic phosphides,which are synthesized from MOF on MOF structure.The synergistic impact of the metal center Co species and the phase conjugation of both kinds of MOFs are responsible for this regulatory phenomenon.Therefore,the catalyst demonstrates excellent properties,demonstrating HER 81 mV(η10)in a 1.0 mol L^(−1)KOH solution and OER 239 mV(η50)low overpotentials.The FeP-CoP_(3)linked dual electrode alkaline batteries,which are bifunctional electrocatalysts,have a good electrocatalytic ability and may last for 50 h.They require just 1.49 V(η50)for total water breakdown.Through this technique,the electrical structure of electrocatalysts may be altered to increase catalytic activity.

Synthesis and application of transition metal phosphides as electrocatalyst for water splitting

With continuous research on photocatalytic water splitting, searching for efficient catalyst for hydrogen evolution reaction(HER) becomes popular topic in addition to main catalyst research. Transition metal phosphides are receiving intense attention due to its abundance in the Earth's crust and comparable catalytic properties to noble metals. In this review, the synthesis approaches, HER reaction mechanism,photocatalytic activity, approaches to improve the activity of transition metal phosphides were reviewed and discussed. It was showed that the transition metal phosphides have great potential to reduce the cost of photocatalyst and promising application on water splitting. The stability problem and participation of poisonous reactant and product in its synthesis reaction limit its application and developing in a certain extent, but with the continuous efforts on the development and improvement of the synthesis methods,transition metal phosphides will find wide application in water splitting.

Highly selective and stable hydrogenation of heavy aromatic-naphthalene over transition metal phosphides

The present study reports a highly selective and stable catalytic approach for producing tetralin, an important chemical, solvent, and H2 storage material. Transition metal phosphides （MOP, Ni2P, Co2P, and Fe2P） were prepared by wet impregnation and temperature-programmed reduction and characterized by X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, EDX mapping, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, brunauer-emmett- teller （BET）, temperature-programmed desorption of ammonia （NH3-TPD）, and fourier transform infrared spectroscopy of pyridine （pyridine-FTIR）. Of all the transition metal phosphides MoP was formed at a lower reduction temperature, which resuited in smaller particle size that enhanced the overall surface area of the catalyst. The existence of weak, moderate, and Lewis acidic sites over MoP were responsible for its high tetralin selectivity （90%） and stability during the 100 h reaction on-stream in a fixed-bed reactor.

A new insight into the promoting effects of transition metal phosphides in methanol electrooxidation

The construction of highly active catalysts for methanol oxidation reaction(MOR)is central to direct methanol fuel cells.Tremendous progress has been made in transition metal phosphides(TMPs)based catalysts.However,TMPs would be partially damaged and transformed into new substances(e.g.,Pt-M-P composite,where M represents a second transition metal)during Pt deposition process.This would pose a large obstacle to the cognition of the real promoting effects of TMPs in MOR.Herein,Co_(2)P co-catalysts(Pt-P/Co_(2)P@NPC,where NPC stands for N and P co-doped carbon)and Pt-Co-P composite catalysts(Pt-CoP/NPC)were controllably synthesized.Electrocatalysis tests show that the Pt-Co-P/NPC exhibits superior MOR activity as high as 1016 m A/mg_(Pt),significantly exceeding that of Pt-P/Co_(2)P@NPC(345 m A/mg_(Pt)).This result indicates that the promoting effect is ascribed primarily to the resultant Pt-Co-P composite,in sharply contrast to previous viewpoint that Co_(2)P itself improves the activity.Further mechanistic studies reveal that Pt-Co-P/NPC exhibits much stronger electron interaction and thus manifesting a remarkably weaker CO absorption than Pt-P/Co_(2)P@NPC and Pt/C.Moreover,Pt-Co-P is also more capable of producing oxygen-containing adsorbate and thus accelerating the removal of surface-bonded CO^(*),ultimately boosting the MOR performance.

Self-supported transition metal phosphide based electrodes as high-efficient water splitting cathodes

Electrolytic water splitting has been considered as a promising technology to produce highly pure H2 by using electrical power produced from wind, solar energy or other fitful renewable energy resources. Combining novel self-supporting structure and high-performance transition metal phosphides （TMP） shows substantial promise for practical application in water splitting. In this review, we try to provide a comprehensive analysis of the design and fabrication of various self-supported TMP electrodes for hydrogen evolution reaction, which are divided into three categories： catalysts growing on carbon-based substrates, catalysts growing on metal-based substrates and free- standing catalyst films. The material structures together with catalytic performances of self-supported electrodes are presented and discussed. We also show the specific strategies to further improve the catalytic performance by elemental doping or incorporation of nanocarbons. The simple and one-step methods to fabricate self-supported TMP electrodes are also highlighted. Finally, the chal- lenges and perspectives for self-supported TMP electrodes in water splitting application are briefly discussed.

Trimetallic synergistic optimization of 0D NiCoFe-P QDs anchoring on 2D porous carbon for efficient electrocatalysis and high-energy supercapacitor

Developing multi-functional and low-cost noble-metal-free catalysts such as transition metal phosphides(TMPs)to replace noble-metal is of practical significance for energy conversion and storage.However,the low-durability and the agglomeration phenomenon during the electrochemical process limit their practical applications.Herein,using metal–organic frameworks(MOFs)as the precursor and a combined strategy of gradient temperature calcination and thermal phosphorization,a 0D/2D heterostructure of NiCoFe-P quantum dots(QDs)anchored on porous carbon was successfully developed as highly efficient electrode materials for overall water splitting and supercapacitors.Owing to this distinctive 0D/2D heterostructure and the synergistic effect of multi-metallic TMPs,the NiCoFe-P/C exhibits excellent electrocatalytic activity and durability of HER(87 mV at 10 mA cm^(-2))and OER(257 mV at 100 mA cm^(-2))in the KOH electrolyte.When NiCoFe-P/C is used as the two electrodes of electrolyzed water,only 1.55 V can drive the current density to 10 m A cm^(-2).At the same time,our NiCoFe-P/C possessed extraordinary property for charge storage.In particular,an ultra-high energy density of 100.8 Wh kg^(-1) was achieved at a power density of 900.0 W kg^(-1) for our assembled hybrid supercapacitor device NiCoFe-P/C(2:1)//activated carbon(AC).This work may open a potential way for the design of 0D/2D hybrid multifunctional nanomaterials based on TMPs QDs.

A revisiting of transition metal phosphide(Cu_(3)P and FeP)nanozymes for two sugar-related reactions

Transition metal phosphides(TMPs)are essential catalysts for some general catalytic reactions.However,their potentials for biological catalysis have seldom been explored.Herein,we investigated the enzyme-like properties of four TMPs(FeP,CoP,Ni_(2)P,and Cu_(3)P)towards two sugar-related reactions.Among the four TMPs,Cu_(3)P nanoparticles(NPs)efficiently catalyzed the hydrolysis of glycosidic bonds as glycoside hydrolase mimics,and FeP NPs possessed both glucose oxidase-like(GOx-like)and peroxidase-like activities,which combined into a cascade reaction for glucose’s simple and one-step colorimetric biosensor without GOx.Cu_(3)P and FeP NPs with distinctive enzyme-like activities have shown unique biological catalysis potentials for further applications with an attractive and challenging goal of developing nanomaterials to mimic natural enzymes,which encourages more efforts to reveal TMP’s capabilities towards biocatalysis.

富磷金属磷化物电催化性能的研究进展

近年来,电催化分解水技术越来越得到广泛关注。提高速率的关键是要找到高效的电催化剂,其中过渡金属磷化物表现出优秀的催化活性和长期稳定性。富磷化合物具有催化活性较大但导电性较差的特点,在实际应用中可合理调控磷化物的电子结构,以获得导电性、催化效能俱佳的电催化剂。综述了近年来电解水析氢的研究进展,重点集中在富磷金属磷化物的研究上,阐述了其合成方法与微结构调控策略,及其在当前电催化材料研究领域面临的挑战和未来的发展前景。

金属磷化物在电解水制氢中的应用研究进展

电解水被认为是目前最有前途的制氢方法之一。基于商用贵金属基催化剂成本高和储量有限的情况,开发低成本、高性能的电催化剂是实现电解水制氢产业化的关键。过渡金属磷化物因具有独特的物化性质和高催化活性而被广泛关注,但导电性和活性位点密度的不足限制了其在工业化制氢中的应用。首先阐述电解水析氢的机理及过渡金属磷化物的重要作用。然后从单金属磷化物、双金属磷化物、改性金属磷化物和结构调控过渡金属磷化物4个方面分析不同种类的过渡金属磷化物以及提升其催化性能的途径,并比较了当前过渡金属磷化物的常用制备方法。最后总结提升催化性能的主要策略,展望过渡金属磷化物未来的机遇和挑战。期望本综述有助于过渡金属磷化物电催化剂的设计开发与应用。

仙人掌状的NC/Co_(x)P自支撑电极用于盐水电解实现高效稳定析氢

设计高效、稳定的析氢催化剂是盐水电解技术发展的必然要求。本文通过原位生长策略在泡沫镍(NF)上生长NC/Co_(x)P@NF催化剂,它由Co_(x)P纳米线阵列与氮掺杂碳纳米片(NC)交替生长组成。在制备过程中,Co(OH)_(2)纳米线通过内源Co^(2+)与2-甲基咪唑的溶解配位作用在NF上原位转化为Co-MOF纳米片。仙人掌状的微观结构使NC/CoxP@NF暴露出丰富的活性位点和离子运输通道,促进了HER催化反应动力学。此外,在分级多孔的NC/CoxP@NF中,纳米线和自支撑纳米片交替生长,进一步增强了材料的结构稳定性。最重要的是,表面聚阴离子(磷酸盐)和NC纳米片保护层的形成提高了催化剂的耐腐性能。最终,NC/CoxP@NF-10表现出优异的析氢性能,在1.0 mol L^(-1)KOH和1.0 mol L^(-1)KOH+0.5 mol L^(-1)NaCl条件下,分别需要107和133 mV的过电位达到10 mA cm^(-2)的电流密度。

磷化铁/生物碳复合材料活化亚硫酸盐降解橙黄Ⅱ的研究

水污染严重影响生态环境和人类健康,染料废水是其中的典型代表。利用酵母细胞作磷源和碳源,通过共沉淀-缺氧热解制备了磷化铁/生物碳复合材料,并将其作为高级氧化反应的催化剂,活化亚硫酸盐降解水体污染物橙黄Ⅱ。材料表征结果表明,磷化铁的主要组成成分为Fe_(2)P和Fe_(3)P。在较优的催化条件下,经120 min吸附和催化联合处理,模拟废水中10 mg/L的橙黄Ⅱ可以被完全去除。催化反应机理分析表明,磷化铁/生物碳复合材料通过活化亚硫酸盐产生硫酸根自由基和羟基自由基,进而实现了橙黄Ⅱ的氧化降解。

过渡金属纳米异质材料在超级电容器中的应用

超级电容器因其具有高功率密度、快速充放电性能、超长的循环寿命的优点被广泛应用。过渡金属磷化物(TMPs)和层状双金属氢氧化物(LDHs)作为电极材料,具有大比表面积和良好的电化学活性等优点,但TMPs的倍率性能和LDHs导电性较差。将TMPs和LDHs复合形成异质结构来实现二者的协同效应,从而能够提高电容器的功率密度和循环寿命。综述了TMPs、LDHs及其构建的异质结电极材料的制备方法,与其在超级电容器方面的应用,并展望了其今后的研究发展方向和未来的应用前景。

一种新型高活性加氢脱硫催化剂:二氧化硅担载的磷化镍(英文)

以硝酸镍和磷酸氢二铵为原料 ,采用程序升温还原方法在 82 3K和氢气气氛中制备了纯相和二氧化硅担载的磷化镍催化剂 ,并采用类似的方法制备了纯相和二氧化硅担载的磷化钼和镍钼磷新型磷化物 .对这些磷化物及其相应硫化物的加氢脱硫活性进行了考察 .结果表明 ,Ni2 P/SiO2 催化剂具有相对较高的二苯并噻吩转化率和联苯选择性 ,Ni2 P/SiO2 对二苯并噻吩加氢脱硫的催化活性甚至高于硫化态的Ni Mo催化剂 .