Surface Engineered Ru_(2)Ni Multilayer Nanosheets for Hydrogen Oxidation Catalysis

The hydrogen oxidation reaction(HOR)in alkaline conditions is of great importance for the application of anion exchange membrane fuel cells(AEMFCs).However,the electrocatalysts for alkaline HOR generally suffer from the disadvantage of sluggish kinetics.Herein,we have fabricated Ru2Ni multilayered nanosheets(Ru2Ni MLNSs)in the layer-by-layer manner and engineered the surface properties via postannealing for efficient alkaline HOR.Detailed investigations reveal that such annealing at different temperatures can alter the surface properties of Ru2Ni MLNSs and thus regulate their adsorption abilities toward*H and*OH.In particular,the optimal catalyst exhibits a mass activity of 4.34 A mgRu−1 at an overpotential of 50 mV,which is 18.1 and 13.2 times higher than those of Ru/C(0.24 A mgRu−1)and Pt/C(0.33 A mgPt−1),respectively.Theoretical calculations indicate that the presence of surface O atoms can facilitate the HOR activity while the excessive coverage of O atoms on Ru2Ni surface leads to the strengthened H binding and the decay of HOR activity.This work not only provides an efficient catalyst for alkaline HOR,but it also may shed new light on the design of high-performance catalysts for electrocatalysis and beyond.We have fabricated Ru2Ni multilayer nanosheets(Ru2Ni MLNSs)and realized the surface engineering via an annealing process.Detailed investigations show that such surface engineering can regulate the surface properties and thus promote the alkaline HOR activity.Consequently,the optimal catalyst exhibits a much higher activity than those of commercial Ru/C and Pt/C and is a promising catalyst for alkaline HOR.

高度多孔的铂铅纳米晶用作高效的多元醇电氧化催化剂（英文）

本论文采用简便的湿化学刻蚀法首次成功合成了具有明确形貌、组分和多孔性的PtPb/Pt多孔纳米晶.由于具有高度开放的三维立体结构和合金效应, PtPb/Pt多孔纳米晶的多元醇电催化性能良好.其中,最优化的Pt_3Pb多孔纳米片在乙二醇氧化反应中的催化活性为1.75 mA cm^(-2)和1.19 A mg_(Pt)^(-1),在丙三醇氧化反应中的催化活性为1.46 mA cm^(-2)和1.00 A mg_(Pt)^(-1),均远远高于商业Pt/C催化剂的催化活性.另外, Pt_3Pb多孔纳米片在乙二醇和丙三醇氧化反应中均表现出优异的电催化稳定性,分别经过20000个循环和5000个循环后,其催化活性没有发生明显衰减且纳米结构没有发生改变.因此, Pt_3Pb多孔纳米片可作为一种非常有发展前景的铂基电催化剂应用于多元醇燃料电池及相关领域中.

Atomically isolated Pd sites within Pd-S nanocrystals enable trifunctional catalysis for direct,electrocatalytic and photocatalytic syntheses of H_(2)O_(2)

Although high-efficiency production of hydrogen peroxide(H_(2)O_(2))can be realized separately by means of direct,electrochemical,and photocatalytic synthesis,developing versatile catalysts is particularly challenging yet desirable.Herein,for the first time we reported that palladium-sulphur nanocrystals(Pd-S NCs)can be adopted as robust and universal catalysts,which can realize the efficient O_(2) conversion by three methods.As a result,Pd-S NCs exhibit an excellent selectivity(89.5%)to H_(2)O_(2)with high productivity(133.6 mol·kgcat^(−1)·h^(−1))in the direct synthesis,along with the significantly enhanced H_(2)O_(2)production activity and stability via electrocatalytic and photocatalytic syntheses.It is demonstrated that the isolated Pd sites can enhance the adsorption of O_(2) and inhibit its O–O bond dissociation,improving H_(2)O_(2)selectivity and reducing H_(2)O_(2)degradation.Further study confirms that the difference in surface atom composition and arrangement is the key factor for different ORR mechanisms on Pd NCs and Pd-S NCs.

Efficient catalytic hydrogen generation by intermetallic platinum-lead nanostructures with highly tunable porous feature

The water-gas shift(WGS) reaction is an essential industrial reaction for upgrading hydrogen(H2) by removing carbon monoxide(CO), while highly efficient platinum(Pt)-based catalysts for WGS with simultaneously high activity and stability are still yet to be developed due to the poisoning issue during the reaction. Herein, we report on the porous PtPb peanut nanocrystals(porous PtPb PNCs) and porous PtPb octahedron nanocrystals(porous PtPb ONCs) with controllable ratios of Pt/Pb as extremely active and stable catalysts towards WGS reaction. It exhibits the composition-dependent activity with porous PtPb PNCs-40/ZnO being the most active for WGS to H_2, 16.9 times higher than that of the commercial Pt/C. The porous PtPb PNCs-40/ZnO also display outstanding durability with barely activity decay and negligible structure and composition changes after ten successive reaction cycles. X-ray photoelectron spectroscopy(XPS) results reveal that the suitable binding energy of Pt 4f_(7/2) and the high ratio of Pt(0)to Pt(II) in porous PtPb PNCs/ZnO and porous PtPb ONCs/ZnO are crucial for the enhanced WGS activity.The CO stripping results indicate the optimized CO adsorption strength on the Pt surface ensure the excellent WGS activity and the outstanding durability. The present work demonstrates an important advance in tuning the porous metal nanomaterials as highly efficient and durable catalysts for catalysis,energy conversion and beyond.

富含缺陷的非晶态与晶态杂化介孔钴钼纳米片高效析氧催化剂

构建具有丰富缺陷且缺陷浓度可调的二维(2D)介孔金属氧化物(氢氧化物)纳米材料作为高效电催化剂仍然是一个巨大的挑战.本工作开发了一种简便有效的一锅溶剂热路线来合成由晶体相Mo_(4)O_(11)和准非晶相氢氧化钴组成的介孔Mo_(x)-Co-O杂化纳米片.由于短链有机胺在高温下的刻蚀作用,合成过程中在Mo_(x)-Co-O杂化纳米片上原位产生了大量的介孔空穴,增加了材料的电化学比表面积.此外,Mo_(x)-Co-O纳米片的尺寸、介孔和晶相/非晶相纳米片上缺陷(本工作中的氧空位)的浓度可以通过控制Mo/Co摩尔比调节.电化学测试表明,2D介孔Mo_(x)-Co-O纳米片表现出优异的析氧反应活性,其中Mo_(0.2)-Co-O纳米片表现出最高的催化活性(在1 mol L^(−1)KOH中10 mA cm^(−2)处的过电位为276 mV).研究发现,Mo_(0.2)-Co-O纳米片具有合适的d带中心和最高浓度的氧空位,这是促成其优异催化活性的两个主要因素.本工作构建具有丰富缺陷(氧空位)和合适d带中心的二维金属氧化物(氢氧化物)的晶相/非晶杂化纳米材料的方法,为设计更高效的催化剂提供了重要启发.

Face-centered cubic structured RuCu hollow urchin-like nanospheres enable remarkable hydrogen evolution catalysis

Ruthenium(Ru)is one of the most promising metals for its versatility in driving a wide range of catalytic reactions.However,owing to the intrinsic preference of hexagonal close-packed(hcp)phase for bulk Ru,currently,it is still challenging to construct Ru-based nanomaterials with face-centered-cubic(fcc)phase for optimizing their performance towards potential applications.Herein,we report a facile wet-chemical method to directly create unconventional fcc-structured Ru-copper hollow urchin-like nanospheres(fcc-RuCu HUNSs)as a class of efficient pH-universal hydrogen evolution reaction(HER)electrocatalyst.Interestingly,this synthetic strategy can be expanded to prepare other fcc-Ru-based alloy nanomaterials.Significantly,the novel fcc-RuCu HUNSs exhibit superior HER performance with the overpotential of only 25,34,40,and 26 m V to reach the current density of 10 mA cm^(-2)in 0.5 M H_(2)SO_(4),0.05 M H_(2)SO_(4),0.1 M KOH,and 1 M KOH,respectively,much lower than those of hcpRuCu HUNSs and commercial Pt/C.Density functional theory(DFT)calculations further indicate that their excellent pH-universal HER performance results from the optimized adsorption free energy of H and work functions.Our work highlights the importance of phase control to design high-efficiency nanocatalysts for relevant catalytic reactions in energy conversion.

Two-dimensional PtPb-PbS heterostructure enables improved kinetics and highlighted bifunctional antipoisoning for methanol electrooxidation

Two-dimensional(2 D) platinum(Pt)-based nanomaterials are considered as the ideal fuel cell catalysts, while their rational synthesis associated with phase control remains a formidable challenge. Herein, we firstly design the novel 2 D Pt-lead-sulphur heterophased nanosheets(Pt Pb S HPNSs) as efficient high-toleration electrocatalysts for methanol oxidation reaction(MOR).They exhibit much higher activity and more highlighted bifunctional antipoisoning abilities than Pt Pb NSs and commercial Pt/C.Further density functional theory(DFT) simulation verifies that the decreased electron density of Pt sites worked by Pb and S makes CO intermediate favorable to desorb, avoiding the formation of CO*-polluted Pt sites. Simultaneously, this heterophased interface effectively weakens the adsorption of S^(2-)-species and improves the S-poisoning tolerance, showing a route to realize nearly innoxious catalysis. The present work highlights the importance of heterophase control in tuning antipoisoning property for 2 D Pt-based nanomaterials, which is key for the rational design of efficient fuel cell anodic catalysts.

H-Implanted Pd Icosahedra for Oxygen Reduction Catalysis: From Calculation to Practice

Although palladium(Pd)has gradually emerged as the most likely candidate to replace platinum(Pt)in the oxygen reduction reaction(ORR),the specific electronic structure of conventional Pd results in too strong Pd–O binding strength and unsatisfactory ORR performance.Herein,guided by density functional theory,we have explored a strategy to expand lattice spacing by implanting hydrogen(H)atoms in Pd nanocrystals(NCs),which realizes decreased electron density to boost ORR.

Highly Distorted Platinum Nanorods for High-Efficiency Fuel Cell Catalysis

Different from studies where less defective platinum(Pt)-based nanomaterials have been widely used to improve the catalysis of the oxygen reduction reaction(ORR)for proton-exchange membrane fuel cells(PEMFCs),herein we have demonstrated that a new class of Pt nanorods(NRs)with a highly distorted configuration can be applied as an advanced,high-efficiency fuel cell catalyst,as transformed from spongy Pt–tellurium NRs(PtTe2 NRs)through sequential chemical and electrochemical aging procedures.The resulting highly distorted Pt NRs exhibit excellent ORR-specific and mass activities of 4.70mA cm−2 and 2.77 Amg−1 Pt at 0.90 V versus the reversible hydrogen electrode(RHE),which are 18.8 and 16.3 times higher than those of commercial Pt/C catalyst,and the mass activity is 6.3 times higher than 2020 U.S.Department of Energy target.Additionally,negligible activity decays were observed after 30,000 cycles.The high ORR performance endows these unique Pt NRs with enhanced activity and lifetimes for practical fuel cell catalysis in comparison with commercial Pt/C,which is consistent with the experimental results.It has been demonstrated that the anomaly of strong electron–lattice coupling suppresses Coulombic repulsion for barrier-free electron transfer while concurrently exposing a large number of active sites,which is a key to superior high-performance fuel cell reactions.