在4H晶相Au纳米带上外延生长非常规晶相4H-Pd基合金纳米结构用于高效甲醇电催化氧化

Pd基合金纳米材料通常具有传统的面心立方(fcc)晶相。本文以密排六方4H相Au(4H-Au)纳米带为模板,外延生长非常规4H晶相的PdFe、PdIr和PdRu,形成4H-Au@PdM(M=Fe、Ir和Ru)核壳合金纳米带。合成的4H-Au@PdFe纳米带被用于碱性环境中甲醇电催化氧化反应(MOR)的催化剂,表现出优越的质量活性(3.69 A·mgPd^(−1)),分别为Pt/C和Pd黑催化剂质量活性的2.4和10.5倍,也跻身于最好的Pd基和Pt基MOR电催化剂之列。这一策略为合理设计和可控合成具有非常规晶相的多金属纳米结构提供了策略,从而为深入研究多金属纳米结构晶相依赖的性质和应用提供了可能。

Wet-chemical synthesis and applications of amorphous metalcontaining nanomaterials

In the past decades,metal-containing nanomaterials have attracted increasing interests owing to their intriguing physicochemical properties and various promising applications.Recent research has revealed that the phase of metal-containing nanomaterials could significantly affect their properties and functions.In particular,nanomaterials with amorphous phase,which possess long-range disordered atomic arrangements,and the amorphous/crystalline heterophase nanostructures comprised of both amorphous and crystalline phases,have exhibited superior performance in various applications,e.g.,catalysis and energy storage.In this review,a brief overview of the recent progress on the wet-chemical synthesis and applications of amorphous and amorphous/crystalline heterophase metal-containing nanomaterials has been provided.Subsequently,on the basis of different categories of metal-containing nanomaterials,including metals,metal alloys,and metal compounds,their synthetic routes and promising applications will be highlighted.Finally,current challenges and some personal perspectives in this emerging research field will be proposed.

Synthesis of amorphous Pd-based nanocatalysts for efficient alcoholysis of styrene oxide and electrochemical hydrogen evolution

Amorphous nanomaterials with long-range disordered structures could possess distinct properties and promising applications,especially in catalysis,as compared with their conventional crystalline counterparts.It is imperative to achieve the controlled preparation of amorphous noble metal-based nanomaterials for the exploration of their phase-dependent applications.Here,we report a facile wet-chemical reduction strategy to synthesize various amorphous multimetallic Pd-based nanomaterials,including PdRu,PdRh,and PdRuRh.The phase-dependent catalytic performances of distinct Pd-based nanomaterials towards diverse catalytic applications have been demonstrated.Specifically,the usage of PdRu nanocatalysts with amorphous and crystalline face-centered cubic(fcc)phases can efficiently switch the ring-opening route of styrene oxide to obtain different products with high selectivity through alcoholysis reaction and hydrogenation reaction,respectively.Moreover,when used as an electrocatalyst for hydrogen evolution reaction(HER),the synthesized amorphous PdRh nanocatalyst exhibits low overpotential and high turnover frequency values,outperforming its crystalline fcc counterpart and most of the reported Pd-based HER electrocatalysts.

Recent advances of Rh-based intermetallic nanomaterials for catalytic applications

Rhodium(Rh)has received widespread attention in fundamental catalytic research and numerous industrial catalytic applications.Compared to homogeneous catalysts,Rh-based nanomaterials as heterogeneous catalysts are much easier to separate and collect after usage,making them more suitable for commercial use.To this purpose,there has been a constant demand in constructing stable and highly active Rh-based nanomaterials.In contrast to Rh-based solid solutions with a random distribution of metallic atoms in the lattice,Rh-based intermetallic compounds(IMCs)with a fixed stoichiometric ratio and an ordered atomic arrangement can ensure the homogenous distribution of active sites and structural stability in the catalytic process.In this review,we concentrate on the fabrication of Rh-based IMCs for catalytic applications.Various synthetic methods and protocols for the controlled preparation of Rh-based IMC are illustrated.Meanwhile,the catalytic applications and corresponding catalytic mechanisms are discussed.In addition,personal perspectives about the remaining challenges and prospects in this field are provided.We believe this review will be useful in directing the development of Rh-based IMC catalysts for heterogeneous catalysis.

Recent Progress on Monoelemental Nanomaterials with Unconventional Crystal Phases

As an important parameter of crystalline materials,the crystal phase describes the periodic atomic arrangement in their structures.For some monoelemental materials,e.g.,carbon and phosphorus,they can exist in more than one crystal phase.The different crystal phases of monoelemental materials result in different physicochemical properties and functions.Therefore,engineering the crystal phase of monoelemental materials gives an effective strategy to modulate their properties and functions.Conventionally,the crystal phase of monoelemental materials can be altered under some harsh conditions,e.g.,high temperature and high pressure.Recently,with the rapid development of nanotechnology,various monoelemental materials with unconventional crystal phases have been well developed on the nanoscale.For example,our group has successfully achieved the synthesis of Au nanomaterials with unconventional hexagonal close-packed(hcp)2H and 4H phases by wetchemical methods,which exhibit distinct optical properties as well as outstanding electrocatalytic performance when compared to those with a thermodynamically stable facecentered cubic(fcc)phase.In this Account,we give a comprehensive overview of the recent development of monoelemental nanomaterials with unconventional crystal phases and their crystal-phase-dependent properties and applications.We first introduce the typical strategies for the synthesis of monoelemental nanomaterials with unconventional crystal phases.By using a wet-chemical reduction method,template-assisted method,and thermal annealing method,monoelemental nanomaterials with unconventional crystal phases can be directly prepared.Besides,unconventional-phase monoelemental nanomaterials can also be obtained via the phase transformation from materials with conventional crystal phases under specific conditions.In addition,some other methods have also been reported for preparing monoelemental nanomaterials with unconventional crystal phases,such as controlled crystallization of amorphous structure,the chemical vapor transport(CVT)method,electrodeposition,galvanic replacement,sputter-deposition,and so on.Subsequently,we summarize the unique structural stability and magnetic,electronic,optical,and other properties of the obtained monoelemental nanomaterials with unconventional crystal phases.We also highlight their promising applications in catalysis and batteries.Finally,we present our personal perspectives on the challenges and future opportunities in this important research field.

Crystal facet-dependent electrocatalytic performance of metallic Cu in CO_(2)reduction reactions

Developing high-performance electrocatalysts for CO_(2) reduction reaction(CO_(2)RR)is crucial since it is beneficial for environmental protection and the resulting value-add chemical products can act as an alternative to fossil feedstocks.Nonetheless,the direct reduction of CO_(2) into long-chain hydrocarbons and oxygenated hydrocarbons with high selectivity remains challenging.Copper(Cu)shows a distinctive advantage that it is the only pure metal catalyst for reducing CO_(2) into multi-carbon(C_(2+))products and the certain facets(e.g.,(100),(111),(111))of Cu nanocrystals exhibit relatively low energy barriers for the formation of specific products(e.g.,CO,HCOOH,CH_(4),C_(2)H_(4),C_(2)H_(5)OH,and other C_(2+) products).Therefore,extensive studies have been carried out to explore the relationship between the facets of Cu nanocrystals and corresponding catalytic products.In this review,we will discuss the crystal facet-dependent electrocatalytic CO_(2)RR performance in metallic Cu catalysts,meanwhile,the detailed reaction mechanisms will be systematically summarized.In addition,we will provide a personal perspective for the future research directions in this emerging field.We believe this review is helpful to guide the design of high-selectivity Cu-based electrocatalysts for CO_(2)RR.

Phase engineering of metal nanocatalysts for electrochemical CO_(2) reduction

The electrochemical CO_(2) reduction reaction(CO_(2)RR)offers a green and sustainable process to convert CO_(2) into valuable chemical stocks and fuels.Metal is one of the most promising types of catalysts to drive an efficient and selective CO_(2)RR.The catalytic performance of metal nanocatalysts is strongly dependent on their structural features.Recently,phase engineering of nanomaterials(PEN)has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO_(2)RR.A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed,and remarkable achievements have been made.This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO_(2)RR.We first introduce the different crystal phases of metal nanocatalysts used in the CO_(2)RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts.After that,detailed discussions of metal nanocatalysts with conventional and unconventional phases,including amorphous phases,are presented.Finally,the challenges and perspectives in this emerging area are discussed.