Earth-abundant amorphous catalysts for electrolysis of water

The generation of hydrogen through the electrolysis of water has attracted attention as a promising way to produce and store energy using renewable energy sources.In this process,a catalyst is very important to achieve a high‐energy conversion efficiency for the electrolysis of water.A good catalyst for water electrolysis should exhibit high catalytic activity,good stability,low cost and good scalability.Much research has been devoted to developing efficient catalysts for both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).Traditionally,it has been accepted that a material with high crystallinity is important to serve as a good catalyst for HER and/or OER.Recently,catalysts for HER and/or OER in the electrolysis of water splitting based on amorphous materials have received much interest in the scientific community owing to the abundant unsaturated active sites on the amorphous surface,which form catalytic centers for the reaction of the electrolysis of water.We summarize the recent advances of amorphous catalysts for HER,OER and overall water splitting by electrolysis and the related fundamental chemical reactions involved in the electrolysis of water.The current challenges confronting the electrolysis of water and the development of more efficient amorphous catalysts are also discussed.

Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over An Ultrafine Co-B Amorphous Catalyst

A novel Co-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of CoCl2 with aqueous NaBH4, which exhibited excellent activity and selectivity during the hydrogenation of cinnamaldehyde to cinnamyl alcohol in liquid phase. The optimum yield of cinnamyl alcohol was 87.6%, much better than the yield of using Raney Ni, Raney Co and other Co-based catalysts.

Ni-B/TiO_2 Amorphous Catalyst Used in Heavy Arenes of Petrochemicals Hydrogenation

A supported Ni-B/TiO2 amorphous catalyst was prepared by impregnation and reduction. It was characterized by XRD, SAED, DSC, XPS, etc.. The catalytic activity of catalyst was measured through the hydrogenation of heavy arenes in petrochemicals for the first time.

Study on the Nanosized Amorphous Ru-Fe-B/ZrO_2 Alloy Catalyst for Benzene Selective Hydrogenation to Cyclohexene

A novel nanosized amorphous Ru-Fe-B/ZrO2 alloy catalyst for benzene selective hydrogenation to cyclohexene was investigated. The superior properties of this catalyst were attributed to the combination of the nanosize and the amorphous character as well as to its textural character. In addition, the concentration of zinc ions, the content of ZrO2 in the slurry, and the pretreatment of the catalyst were found to be effective in improving the activity and the selectivity of the catalyst.

Hydrogenation of Furfural to Furfuryl Alcohol over Co-B Amorphous Catalysts Prepared by Chemical Reduction in Variable Media

Five Co-B amorphous alloy catalysts were prepared by chemical reduction in different media, including pure water and pure ethanol as well as the mixture of ethanol and water with variable ethanol content, Their catalytic properties were evaluated using liquid phase furfural hydrogenation to furfuryl alcohol as the probe reaction. It was found that the reaction media had no significant influence on either the amorphous structure of the Co-B catalyst or the electronic interaction between metallic Co and alloying B. This could successfully account for the fact that all the as-prepared Co-B catalysts exhibited almost the same selectivity to furfuryl alcohol and the same activity per surface area （ Rs ）, which could be considered as the intrinsic activity, since the nature of active sites remained unchanged. However, the activity per gram of Co （ R^mH ） of the as-prepared Co-B catalysts increased rapidly when the ethanol content in the water-ethanol mixture used as the reaction medium for catalyst preparation increased. This could be attributed to the rapid increase in the surface area possibly owing to the presence of more oxidized boron species which could serve as a support for dispersing the Co-B amorphous alloy particles.

A Novel Ultrafine Ru-B Amorphous Alloy Catalyst for Glucose Hydrogenation to Sorbitol

An ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4 in aqueous solution, which exhibited perfect selectivity to sorbitol (~100%) and very high activity during the liquid phase glucose hydrogenation, much higher than the corresponding crystallized Ru-B, the pure Ru powder, and Raney Ni catalysts. The correlation of the catalytic activity to both the structural and surface electronic characteristics was discussed briefly.

Effect of TiO_2 Support on the Composition, Morphology and Catalytic Property of the NiB Amorphous Alloy Catalyst

Both the unsupported and supported NiB amorphous alloy catalysts (NiB and NiB/TiO2) were prepared by the chemical reduction method. Their catalytic activities were tested by the hydrogenation of sulfolene. The interactions between the NiB alloy and TiO2 were discussed for the first time by using XRD, ICP, SEM and TEM.

Preparation and Application of Supported Amorphous Alloy Catalyst CoP/TiO_2

A new supported amorphous catalyst CoP/TiO2 was prepared by chemical reduction and characterized by ICP, XRD, TEM, BET and DSC. Its application in decomposing PH3 to high purity phosphor and its catalytic activity were studied. The decomposition rate is over 95% at 450 ℃. For comparison, unsupported CoP amorphous catalyst was prepared by the same method. The result suggests that CoP/TiO2 exhibits higher thermal stability and catalytic activity than CoP, which is attributed to the high dispersion of CoP alloy particles on the support-TiO2.

Effect of Lanthanum on Performance of RuB Amorphous Alloy Catalyst for Benzene Selective Hydrogenation

The effect of La on the performance of a supported RuB amorphous alloy catalyst for benzene selective hydrogenation was studied by means of activity and selectivity tests, such as HRTEM, SAED, XPS, and XRD. The results show that the addition of La to RuB amorphous alloy catalyst can evidently increase the activity and improve the thermal stability of RuB amorphous alloy to refrain its crystallization. The promoting effect of La on the activity of RuB amorphous alloy catalyst is because of the high dispersion of the active components.

Preparation of Uniform Ni-B Amorphous Alloy Catalyst on CNTs and its Performance for Acetylene Selective Hydrogenation

Uniform Ni-B amorphous alloys about 14 nm have been prepared on CNTs-A support,named Ni-B/CNTs-A. In comparison with the Ni-B/CNTs amorphous catalyst, Ni-B/CNTs-A showed higher nickel loading, determined by ICP and better catalytic activity and ethylene selectivity in the acetylene hydrogenation reaction.

Effect of Metallic Additives on Structure and Catalytic Properties of Supported NiPB/SiO_2 Catalyst

A new preparation method was proposed to deposit amorphous alloys alloys containing NiPand metallic metallic additives such as Fe.Co. and Cu.The different effects of metallic additive onstructure and catalytic properties of supported amorphous NiMPB/SiO2 (M=Fe, Co. Cu) cafalysts were observed,and the improvement of catalytic activity due to heating pretreatment in hydrogenwas found.

Design of earth-abundant amorphous transition metal-based catalysts for electrooxidation of small molecules:Advances and perspectives

Electrochemical oxidation of small molecules(e.g.,water,urea,methanol,hydrazine,and glycerol)has gained growing scientific interest in the fields of electrochemical energy conversion/storage and environmental remediation.Designing cost-effective catalysts for the electrooxidation of small molecules(ESM)is thus crucial for improving reaction efficiency.Recently,earth-abundant amorphous transition metal(TM)-based nanomaterials have aroused souring interest owing to their earth-abundance,flexible structures,and excellent electrochemical activities.Hundreds of amorphous TM-based nanomaterials have been designed and used as promising ESM catalysts.Herein,recent advances in the design of amorphous TM-based ESM catalysts are comprehensively reviewed.The features(e.g.,large specific surface area,flexible electronic structure,and facile structure reconstruction)of amorphous TM-based ESM catalysts are first analyzed.Afterward,the design of various TM-based catalysts with advanced strategies(e.g.,nanostructure design,component regulation,heteroatom doping,and heterostructure construction)is fully scrutinized,and the catalysts’structure-performance correlation is emphasized.Future perspectives in the development of cost-effective amorphous TM-based catalysts are then outlined.This review is expected to provide practical strategies for the design of next-generation amorphous electrocatalysts.

Fabrication of amorphous PdNiCuP nanoparticles as efficient bifunctional and highly durable electrocatalyst for methanol and formic acid oxidation

Highly active and durable electrocatalytic materials towards small molecules electro-oxidation reaction are critical to the large-scale commercial applications of direct liquid fuel cells.Unfortunately,current nanocrystalline electrocatalysts normally suffer from low catalytic efficiency,severe CO poisoning and rapid activity decay.Herein,we report a novel amorphous Pd Ni Cu P catalyst synthesized with laser liquid ablation as a potential settlement to this issue.The as-obtained amorphous Pd Ni Cu P catalyst exhibits enhanced electrocatalytic performance with the mass activity of 1.61 A mg^(-1)and 737.8 m A mg^(-1)towards methanol oxidation reaction(MOR)and formic acid oxidation reaction(FAOR),respectively.Moreover,amorphous Pd Ni Cu P displays excellent operation stability and CO-poisoning resistance in both alkaline and acidic medium.P was proposed to play the decisive role for forming the amorphous structure and maintaining the catalytic stability in MOR and FAOR processes.This work provided insights for the ration design of active and durable amorphous electrocatalysts applied in direct liquid fuel cells.

Immobilization of Chiral Catalyst on Amorphous Al2O3 for the Selective Hydrogenation of Ethyl 1H-Indole-2-carboxylate

Ru-B/γ-Al2O3 catalyst was prepared by reductant impregnation method,which was applied in the selective hydrogenation of ethyl 1H-indole-2-carboxylate for producing ethyl 2,3,3a,7a-tetrahydro-1H-indole-2-carboxylate with hydrogen as reductant.Furthermore,we discussed the influences of substrate concentration,reaction solvent,hydrogenation temperature,initial hydrogen pressure and reaction time on the catalytic performance of the as-prepared catalyst.The obtained Ru-B/γ-Al2O3 catalyst showed a high-efficiency for the selective hydrogenation of ethyl 1H-indole-2-carboxylate（＞99％ conversion and selectivity） in i-propanol used as solvent at a concentration of 10％（mass fraction） of ethyl 1H-indole-2-carboxylate,a pressure of hydrogen of 6 MPa and a reaction temperature of 373 K.

Magnetically stabilized bed reactor for selective hydrogenation of olefins in reformate with amorphous nickel alloy catalyst

A magnetically stabilized bed （MSB） reactor for selective hydrogenation of olefins in reformate was developed by combining the advantages of MSB and amorphous nickel alloy catalyst. The effects of operating conditions, such as temperature, pressure, liquid space velocity, hydrogen-to-oil ratio, and magnetic field intensity on the reaction were studied. A mathematical model of MSB reactor for hydrogenation of olefins in reformate was established. A reforming flow scheme with a post-hydrogenation MSB reactor was proposed. Finally, MSB hydrogenation was compared with clay treatment and conventional post-hydrogenation.

Recent advances of amorphous-phase-engineered metal-based catalysts for boosted electrocatalysis

Amorphous metal-based catalysts(AMCs)have sparked intense research interests in the field of electrocatalysis elicited by their hallmark features such as unlimited volume and morphology,manipulated electronic structures,enriched defects,and unsaturated surface atom coordination.Nevertheless,the manipulation of the amorphous phase in metal-based catalysts is so far impractical,and thus their electrocatalytic mechanism yet remains ambiguous.In this review,the latest advances in AMCs are systematically reviewed,covering amorphous-phase engineering strategy,structure manipulation,and amorphization of various material categories for electrocatalysis.Specifically,a series of applications of AMCs in electrocatalysis for the oxygen reduction reaction(ORR),hydrogen evolution reaction(HER),and oxygen evolution reaction(OER)are summarized based on the classification criteria of substances.Finally,we put forward current challenges that have not yet been clarified in the field of AMCs,and propose possible solutions,particularly from the perspective of the evolution of electron microscopy.It is expected to promote the understanding of the amorphization-catalysis relationship and provide a guideline for designing high-performance electrocatalysts.

含双晶格氧的无定形锆掺杂锰氧化物选择性高效氧化5-羟甲基糠醛为2,5-呋喃二羧酸

晶格氧介导的氧化还原反应可以将有机物选择性氧化为高附加值产物,是实现生物质资源高值化利用的重要途径.其关键科学难题在于:如何使催化材料同时具有较低的晶格氧(O_(L))结合能以产生活性O_(L),以及较高的O_(L)结合能以保持其在催化过程中的结构稳定性.在本工作中,我们制备了无定形锆掺杂的锰氧化物(amor-Zr:MnO_(x))催化材料,并证实其同时具有高活性的O_(L)以及高稳定性的O_(L).以5-羟甲基糠醛(HMF)的选择性氧化为反应模型,amor-Zr_(0.2)MnO_(x)催化剂实现了HMF的高效选择性氧化,产物中2,5-呋喃二甲酸(FDCA)的选择性高达99%,1小时内FDCA产率高达3600μmol_(FDCA)g_(cat)^(-1)h^(-1),在类似反应条件下其性能优于大多数Mn基和相关过渡金属氧化物基催化材料.实验和理论研究表明,amor-Zr:MnO_(x)的优异性能源于其同时含有两种O_(L).首先,锆提高了锰相邻的O_(L)的氧化活性,并促进了反应后氧空位对O_(2)的吸附/活化,获得活性O_(L)且同步促进催化反应中O_(L)的再生;锆相邻的O_(L)具有较低的反应活性,有利于催化材料保持结构稳定性.本工作有望为理解晶格氧的氧化机制以及高活性催化材料的设计提供思路.