PdMo bimetallene for oxygen reduction catalysis.

The efficient interconversion of chemicals and electricity through electrocatalytic processes is central to many renewable-energy initiatives. The sluggish kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER)1-4 has long posed one of the biggest challenges in this field, and electrocatalysts based on expensive platinum-group metals are often required to improve the activity and durability of these reactions. The use of alloying5-7, surface strain8-11 and optimized coordination environments12 has resulted in platinum-based nanocrystals that enable very high ORR activities in acidic media; however, improving the activity of this reaction in alkaline environments remains challenging because of the difficulty in achieving optimized oxygen binding strength on platinum-group metals in the presence of hydroxide. Here we show that PdMo bimetallene-a palladium-molybdenum alloy in the form of a highly curved and sub-nanometre-thick metal nanosheet-is an efficient and stable electrocatalyst for the ORR and the OER in alkaline electrolytes, and shows promising performance as a cathode in Zn-air and Li-air batteries. The thin-sheet structure of PdMo bimetallene enables a large electrochemically active surface area (138.7 square metres per gram of palladium) as well as high atomic utilization, resulting in a mass activity towards the ORR of 16.37 amperes per milligram of palladium at 0.9 volts versus the reversible hydrogen electrode in alkaline electrolytes. This mass activity is 78 times and 327 times higher than those of commercial Pt/C and Pd/C catalysts, respectively, and shows little decay after 30,000 potential cycles. Density functional theory calculations reveal that the alloying effect, the strain effect due to the curved geometry, and the quantum size effect due to the thinness of the sheets tune the electronic structure of the system for optimized oxygen binding. Given the properties and the structure-activity relationships of PdMo metallene, we suggest that other metallene materials could show great promise in energy electrocatalysis.

Systematic Engineering on Ni-Based Nanocatalysts Effectively Promote Hydrogen Evolution Reaction.

Designing a synthesis of ultra-small Ni-based nanomaterials with high intrinsic activity and stability in alkaline hydrogen evolution reaction (HER) is a major challenge. Herein, a series of noble metal doped ultra-small size (4 nm) M-Ni/NiO nanoparticles supported on CNT are rationally designed by a solvent-free microwave reduction method that is fast (60 s), simple, includes no surfactants, extensive (>1 g), and has high yield (82.7%). The Ir-Ni/NiO@CNT has superior performance with a low overpotential of 24.6 mV at 10 mA cm-2 . In addition, the turnover frequency (TOF) value up to 2.51 s-1 and the exchange current density reaches 4.34 mA cm-2 , indicating that the catalyst has better intrinsic catalytic activity. It is further proved by density functional theory (DFT) that the NiO surface is conducive to the adsorption of OH* in the Volmer step while the Ni is inclined to adsorb H*, which synergistically promotes the water-splitting reaction, thereby increasing the catalytic rate of HER. It is believed that this work will provide valuable contributions and inspirations toward the large-scale production of high-performance Ni-based electrocatalysts for HER.

High Valence M-Incorporated PdCu Nanoparticles (M = Ir, Rh, Ru) for Water Electrolysis in Alkaline Solution.

The high-valence metal catalysts show extraordinary talent in various electrochemical reactions. However, there is no facile method to synthesize high-valence noble metal-based materials. Herein, we synthesized the different high valence noble metal M-incorporated PdCu nanoparticles (M = Ir, Ru, Rh) by the assistant of Fe3+ and exhibit excellent performance for water electrolysis. In 0.1 M KOH, the OER and HER mass activities of Ir16-PdCu/C were 50.5 and 16.5 times as much as PdCu/C, and achieved a current density of 10 mA cm-2 at 1.63 V when worked for overall water splitting. DFT calculation revealed that the incorporating of high valence Ir could optimize the binding energy of the intermediate products, and promote the evolution of oxygen and hydrogen. Ex situ XPS shows that the huge amount of oxidized Ir (V) formed in OER could promote the formation of O-O bonds.

Ordered Vacancies on the Body-Centered Cubic PdCu Nanocatalysts.

Defect engineering has become one of the important considerations in today's electrocatalyst design. However, the vacancies in the ordered crystal structure (especially body-centered cubic (bcc) and the effect of ordered vacancies (OVs) on the electronic fabric have not been researched yet. In this work, we report the inaugural time of the generation of OVs in the bcc architecture and discuss the insight of the modulation system of the material and its part in the electrochemical N2 reduction reaction (NRR). OV-PdCu-2 achieves the highest Faradaic efficiency value of 21.5% at 0.05 V versus RHE. When the potential increases to 0 V versus RHE, the highest ammonia yield is 55.54 µg h-1 mgcat-1, which is significantly better than the unetched PdCu nanoparticles (12.83 µg h-1 mgcat-1). It is the latest reported catalyst to date in the NRR process at 0 V versus RHE (see Supporting Information).

Superfast Synthesis of Densely Packed and Ultrafine Pt-Lanthanide@KB via Solvent-Free Microwave as Efficient Hydrogen Evolution Electrocatalysts.

At present, it is still a great challenge to synthesize refractory Pt-based electrocatalysts with excellent active specific surface area, specific activity, and stability by a simple method. Here, a superfast and solvent-free microwave strategy is reported to synthesize refractory ultrafine (≈3 nm) Pt-lanthanide@Ketjen Black (PtM@KB, M = La, Gd, Tb, Er, Tm, and Yb) alloy with densely packed as efficient hydrogen evolution electrocatalysts in a domestic microwave oven for the first time. The optimized Pt61 La39 @KB delivers excellent hydrogen evolution reaction (HER) activity with a low overpotential of 38 mV (10 mA cm-2 ) and a high TOF value of 44.13 s-1  (100 mV) in 0.5 m H2 SO4 , and performs well in 1.0 m KOH. This method can also be used to grow catalysts on carbon cloth (CC) directly. PtLa@CC shows an overpotential of 99 mV (1000 mA cm-2 ) in 0.5 m H2 SO4 and can maintain activity after 500 h. Theoretical calculations reveal the enhanced stability and activity owing to the higher vacancy formation energy of Pt atoms and the optimized value of ΔGH* . Solvent-free microwave strategy constitutes a significant insight into the development of refractory electrocatalyst with ultrafine size and highly dense, which can also work well at high current densities.

Exclusive Strain Effect Boosts Overall Water Splitting in PdCu/Ir Core/Shell Nanocrystals.

Core/shell nanocatalysts are a class of promising materials, which achieve the enhanced catalytic activities through the synergy between ligand effect and strain effect. However, it has been challenging to disentangle the contributions from the two effects, which hinders the rational design of superior core/shell nanocatalysts. Herein, we report precise synthesis of PdCu/Ir core/shell nanocrystals, which can significantly boost oxygen evolution reaction (OER) via the exclusive strain effect. The heteroepitaxial coating of four Ir atomic layers onto PdCu nanoparticle gives a relatively thick Ir shell eliminating the ligand effect, but creates a compressive strain of ca. 3.60%. The strained PdCu/Ir catalysts can deliver a low OER overpotential and a high mass activity. Density functional theory (DFT) calculations reveal that the compressive strain in Ir shell downshifts the d-band center and weakens the binding of the intermediates, causing the enhanced OER activity. The compressive strain also boosts hydrogen evolution reaction (HER) activity and the strained nanocrystals can be served as excellent catalysts for both anode and cathode in overall water-splitting electrocatalysis.

Interfacial Engineering in PtNiCo/NiCoS Nanowires for Enhanced Electrocatalysis and Electroanalysis.

Searching for new anti-poisoning Pt-based catalysts with enhanced activity for alcohol oxidation is the key in direct alcohol fuel cells (DAFCs). However, in the traditional strategy for designing bimetallic or multimetallic alloy is still difficult to achieve a satisfactory heterogeneous electrocatalyst because the activity often depends on only the surface atoms. Herein, we fabricate the multicomponent active sites by creating a sulfide structure on 1D PtNiCo trimetallic nanowires (NWs), to give a PtNiCo/NiCoS interface NWs (IFNWs). Owing to the presence of sulfide interfaces, the PtNiCo/NiCoS IFNWs enable an impressive methanol/ethanol oxidation reaction (MOR/EOR) performance and excellent anti-CO poisoning tolerance. They have the MOR and EOR mass activities of 2.25 Amg-1 Pt and 1.62 Amg-1 Pt , around 1.26, 3.21 and 1.46, 2.96 times higher than those of PtNiCo NWs and commercial Pt/C, respectively. CO-stripping and XPS measurements further demonstrate that the new interfacial structure and optimal bonding of Pt-CO can result in accelerating the removal of surface adsorbed carbonaceous intermediates. Moreover, such a unique structure has also demonstrated a much-improved ability for the electrochemical detection of some important molecules (H2 O2 and NH2 NH2 ).

Multimetal Borides Nanochains as Efficient Electrocatalysts for Overall Water Splitting.

The development of cost-efficient, active, and stable electrode materials as bifunctional catalysts for electrochemical water splitting is crucial to high-performance renewable energy storage and conversion devices. In this work, the synthesis of Co-based multi-metal borides nanochains with amorphous structure is reported for boosting the oxygen evolution (OER) and hydrogen evolution reactions (HER) by one-pot NaBH4 reduction of Co2+ , Ni2+ , and Fe2+ under ambient temperature. In all the investigated Co-based metal borides, NiCoFeB nanochains show the excellent OER performance with a low overpotential of 284 mV at 10 mA cm-2 and Tafel slope of 46 mV dec-1 , respectively, together with excellent catalytic stability, and robust HER performance with an overpotential of 345 mV at 10 mA cm-2 . The density functional theory (DFT) calculations reveal that the excellent electrocatalytic performance is mainly attributed to optimal electronic structure by tuning the Co-3d band activities by the incorporation of Ni and Fe for enhanced water splitting via the potentially existed Co0 state. Moreover, the electrolyzer using NiCoFeB nanochains as anode and cathode offers 10 mA cm-2 at a cell voltage of 1.81 V, comparable to commercial Pt/C // Ir/C, providing a simple method to design and explore highly efficient and cheap bifunctional electrocatalysts for overall water splitting.

A hierarchical cobalt/carbon nanotube hybrid nanocomplex-based ratiometric fluorescent nanosensor for ultrasensitive detection of hydrogen peroxide and glucose in human serum.

Highly sensitive detection of H2O2 and glucose is critical for fundamental research and disease diagnosis. A ratiometric sensor can simultaneously afford two readout signals that provide an internally normalized response to change, thereby reducing false results and improving detection accuracy. A novel ratiometric fluorescent nanosensor for ultrasensitive detection of hydrogen peroxide and glucose was constructed on the basis of the peroxidase-like properties of a hierarchical cobalt/carbon nanotube hybrid nanocomplex (Co-CNT). The as-prepared Co-CNT catalyzes the transformation of the non-fluorescent Amplex Red (AR) into a fluorescent derivative and the transformation of fluorescent scopoletin (SC) into a non-fluorescent derivative in the presence of H2O2. The sensing system changes colour from yellow to blue, which can be clearly seen with the naked eye. With the fluorescence ratio of AR to SC as readout, the detection limit of H2O2 reaches as low as 100 nM. The developed assay is further utilized for determining H2O2-related oxidase reactions with the glucose and glucose oxidase system as model. Glucose can be selectively and sensitively detected as low as 150 nM. Satisfactory recoveries are obtained for glucose detection in serum samples. The developed assay is simple in terms of preparation and operation and provides a straightforward method for cost-effective and reliable detection of H2O2 and H2O2-related reactions in clinical diagnosis and biomedical applications. Graphical abstract.

Defects and Interfaces on PtPb Nanoplates Boost Fuel Cell Electrocatalysis.

Nanostructured Pt is the most efficient single-metal catalyst for fuel cell technology. Great efforts have been devoted to optimizing the Pt-based alloy nanocrystals with desired structure, composition, and shape for boosting the electrocatalytic activity. However, these well-known controls still show the limited ability in maximizing the Pt utilization efficiency for achieving more efficient fuel cell catalysis. Herein, a new strategy for maximizing the fuel cell catalysis by controlling/tuning the defects and interfaces of PtPb nanoplates using ion irradiation technique is reported. The defects and interfaces on PtPb nanoplates, controlled by the fluence of incident C+ ions, make them exhibit the volcano-like electrocatalytic activity for methanol oxidation reaction (MOR), ethanol oxidation reaction (EOR), and oxygen reduction reaction (ORR) as a function of ion irradiation fluence. The optimized PtPb nanoplates with the mixed structure of dislocations, subgrain boundaries, and small amorphous domains are the most active for MOR, EOR, and ORR. They can also maintain high catalytic stability in acid solution. This work highlights the impact and significance of inducing/controlling the defects and interfaces on Pt-based nanocrystals toward maximizing the catalytic performance by advanced ion irradiation strategy.

Effect of plasma-activated water on the formation of endogenous wheat starch-lipid complexes during extrusion.

The aim of this study was to investigate the effect of plasma-activated water (PAW) during extrusion on the formation of endogenous starch complexes with wheat starch (WS) as a model material. Using PAW during the extrusion process resulted in an increase in amylose content from 27.87 % to 30.07 %. Results from Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry indicated that the PAW facilitated the formation of endogenous starch-lipid complexes during extrusion. PAW120 (distilled water treated by plasma for 120 s) showed a better promotion effect than PAW60 (distilled water treated by plasma for 60 s). EWS120 (WS extruded using PAW120) exhibited lower peak viscosity and swelling power, but higher solubility, particle size, and resistant starch content compared with EWS0 (WS extruded using distilled water) and EWS60 (WS extruded using PAW60). In a word, the acidic substances in PAW may lead to hydrolysis of starch and generate more amylose, thus improving the amount of endogenous starch-lipid complexes. The present study provides a novel extrusion method to obtain modified starch with higher RS content than common extrusion, which has potential application in the industrial production of functional foods with low glycemic index.

Effect of ultrasound-pretreated starch on the formation, structure and digestibility of starch ternary complexes from lauric acid and ß-lactoglobulin.

Starch, lipids, and proteins are key macronutrients in starchy foods. Their interactions during processing can form starch-lipid-protein ternary complexes, significantly affecting food quality. Ultrasonic treatment, as a common processing method, is expected to regulate the quality of starchy foods by influencing the formation of ternary complexes. This study aimed to understand the effect of ultrasonic pretreatment on the formation of starch-lipid-protein ternary complexes using various types of starches. Wheat starch (WS), maize starch (MS), and potato starch (PS) were gelatinized and treated with ultrasound at various power densities (0-40 W/L) to form complexes with lauric acid (LA) and ß-lactoglobulin (ßLG), respectively. Ultrasound increased the amylose content of gelatinized WS, MS, and PS and shifted their chain length distribution towards the short chains. Results from Fourier transform infrared spectroscopy, laser confocal micro-Raman, X-ray diffraction, and differential scanning calorimetry showed that the largest amount of WS-LA-ßLG complexes was formed at the ultrasonic power density of 10 W/L, and MS-LA-ßLG and PS-LA-ßLG complexes at 20 W/L. Additionally, ultrasound enhanced the content of resistant starch (RS) in the starch-LA-ßLG complexes. The RS content increased from 14.12 % to 18.31 % for WS-LA-ßLG, and from 19.18 % and 20.69 % to 27.60 % and 28.63 % for MS-LA-ßLG and PS-LA-ßLG complexes, respectively. This study presents an approach for facilitating the formation of ternary complexes, contributing to the development of low-GI functional foods.

Porous PdWM (M = Nb, Mo and Ta) Trimetallene for High C1 Selectivity in Alkaline Ethanol Oxidation Reaction.

Direct ethanol fuel cells are among the most efficient and environmentally friendly energy-conversion devices and have been widely focused. The ethanol oxidation reaction (EOR) is a multielectron process with slow kinetics. The large amount of by-product generated by incomplete oxidation greatly reduces the efficiency of energy conversion through the EOR. In this study, a novel type of trimetallene called porous PdWM (M = Nb, Mo and Ta) is synthesized by a facile method. The mass activity (15.6 A mgPd -1 ) and C1 selectivity (55.5%) of Pd50 W27 Nb23 /C trimetallene, obtained after optimizing the compositions and proportions of porous PdWM, outperform those of commercial Pt/C (1.3 A mgPt -1 , 5.9%), Pd/C (5.0 A mgPd -1 , 7.2%), and Pd97 W3 /C bimetallene (9.5 A mgPd -1 , 14.1%). The mechanism by which Pd50 W27 Nb23 /C enhances the EOR performance is evaluated by in situ Fourier transform infrared spectroscopy and density functional theory calculations. It is found that W and Nb enhance the adsorption of CH3 CH2 OH and oxophilic high-valence Nb accelerates the subsequent oxidation of CO and CHx species. Moreover, Nb promotes the cleavage of CC bonds and increases the C1 selectivity. Pd60 W28 Mo12 /C and Pd64 W27 Ta9 /C trimetallene synthesized by the same method also exhibit excellent EOR performance.

Solvent-free microwave synthesis of ultra-small Ru-Mo2C@CNT with strong metal-support interaction for industrial hydrogen evolution.

Exploring a simple, fast, solvent-free synthetic method for large-scale preparation of cheap, highly active electrocatalysts for industrial hydrogen evolution reaction is one of the most promising work today. In this work, a simple, fast and solvent-free microwave pyrolysis method is used to synthesize ultra-small (3.5 nm) Ru-Mo2C@CNT catalyst with heterogeneous structure and strong metal-support interaction in one step. The Ru-Mo2C@CNT catalyst only exhibits an overpotential of 15 mV at a current density of 10 mA cm-2, and exhibits a large turnover frequency value up to 21.9 s-1 under an overpotential of 100 mV in 1.0 M KOH. In addition, this catalyst can reach high current densities of 500 mA cm-2 and 1000 mA cm-2 at low overpotentials of 56 mV and 78 mV respectively, and it displays high stability of 1000 h. This work provides a feasible way for the reasonable design of other large-scale production catalysts.

Pt-on-Pd Dendritic Nanosheets with Enhanced Bifunctional Fuel Cell Catalytic Performance.

Pd-Pt bimetallic nanocrystals have become appealing in the electrocatalytic field by virtue of their synergy effects derived from the electronic coupling between two metals. Herein, a facile seed-mediated growth approach is reported for synthesis of Pt-on-Pd dendritic nanosheets (DNSs) through the growth of Pt branches on ultrathin Pd nanosheets (NSs). The as-obtained Pt-on-Pd DNSs exhibit superior catalytic activity toward both oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR), with mass activities (MAs) 2.2 times higher for ORR and 3.4 times higher for MOR than commercial Pt/C catalysts. Moreover, these spatially separated Pt branches supported on 2D NSs also endow the Pt-on-Pd DNSs with impressive durability for ORR with only 18.9% loss in MA, whereas the Pt/C catalyst loses 50.0% after 10,000-cycle accelerated durability tests. This 2D DNS architecture can be extended to other 2D metallic NS substrates for constructing Pt-based electrocatalysts with excellent electrocatalytic performance.

Interface modulation of twinned PtFe nanoplates branched 3D architecture for oxygen reduction catalysis.

Highly-branched dendritic Pt-based nanocrystals possess great potential in catalyzing the oxygen reduction reaction (ORR), but encounter performance ceiling due to their poor thermal and electrochemical stability. Here, we present a novel PtFe nanodendrites (NDs) branched with two-dimensional (2D) twinned nanoplates rather than conventional 1D nanowires, which breaks the ORR performance ceiling of dendritic catalysts by inducing the unique Pt-skin configuration via rationally thermal treatment. By further hybridizing the Pt-skin PtFe NDs/C with amino-functionalized ionic liquids (ILs), we achieve an unprecedented mass activity of 3.15 A/mgPt at 0.9 V versus reversible hydrogen electrode (RHE) in the PtFe-based ORR electrocatalytic system. They also show excellent electrocatalytic durability for ORR with negligible activity decay and no apparent structural change after 20,000 cycles, in sharp contrast to the nanowires branched PtFe NDs counterpart. The remarkable catalytic performance is attributed to a combination of several structural features, including 2D morphology, twin boundary, partially ordered phase and strong coordination with amino group. This work highlights the significance of stabilizing electrocatalytic structures via morphology tuning, which thus enables further surface and interface modification for performance breakthrough in ORR electrocatalysis.

[Association of cathepsin L with coronary heart disease and its risk factors].

OBJECTIVE: To explore the relationship of cathepsin L (CatL) with coronary heart disease (CHD), severity of coronary stenosis and risk factors of CHD. METHODS: A total of 137 CHD patients and 48 controls were included in the study, to determined the serum levels of CatL, high sensitive C reactive protein (hs-CRP), fasting glucose (FBS), total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), apolipoprotein A1(Apo-A1) and apolipoprotein B. All the subjects were invited for a coronary angiography, using the sum of the Gensini scores to assess the severity of coronary artery stenosis. RESULTS: Serum CatL levels were significantly higher in CHD patients (5.63 +/= 0.12 microg/L) than non-CHD subjects (3.93 +/= 0.22 microg/L, P<0.01). CatL was an independent risk factor of CHD in Logistic regression analysis [Exp(B)=2.341, 95%CI 1.567 approximately 3.496, P<0.01]. Serum CatL levels were associated positively with the Gensini scores(r=0.228, P<0.01); In fact, CatL was an independent correlator of Gensini scores (P<0.05). CatL inversely associated with HDL-C (r=-0.228, P<0.01) and ApoA1(r=-0.187, P<0.05), and positively with FBS(r=0.161, P<0.05). CONCLUSION: CatL is involved in the pathogenesis of CHD. Serum CatL levels could reflect the severity of coronary luminal narrowings. CatL might participate in glucose and lipid metabolic disorders.

Rh-doped PdAg nanoparticles as efficient methanol tolerance electrocatalytic materials for oxygen reduction.

Direct methanol fuel cells (DMFCs) have received extensive attention on their high efficiency, high reliability, and no carbon emission. Unfortunately, the poor methanol tolerance and sluggish oxygen reduction reaction (ORR) at cathode have seriously hindered their further development. Herein we report the synthesis of a new class of Rh-doped PdAg alloy nanoparticles (NPs) for boosting ORR activity with high methanol tolerance capacity concurrently. The ORR mass activity of typical Rh4Pd40Ag56 NPs is 4.2 times higher than that of commercial Pt catalyst. Moreover, it shows a great methanol tolerance capability by maintaining 92.4% in ORR mass activity in alkaline solution with 0.1 mol L-1 methanol, against a big decrease of almost 100% for commercial Pt. Even after 30,000 potential cycles with 1.0 mol L-1 methanol, Rh4Pd40Ag56 NPs still retain ORR mass activity of up to 68.3%. DFT calculations reveal that excellent ORR performance with excellent methanol tolerance originates the active d-band-pinning engineering for an efficient site-independent electron-transfer. A generalized d-band mediated fine electron-transfer tuning path has blueprinted for effectively minimizing intrinsic ORR barriers with high current density. The present work highlights the key role of Rh doping in enhancing the ORR activity and methanol tolerance ability of PdAg NPs for future high-performance DMFCs.

Ultrathin PtNiM (M = Rh, Os, and Ir) Nanowires as Efficient Fuel Oxidation Electrocatalytic Materials.

The development of new electrocatalysts with high activity and durability for alcohol oxidation is an emerging need of direct alcohol fuel cells. However, the commonly used Pt-based catalysts still exhibit drawbacks including limited catalytic activity, high overpotential, and severe CO poisoning. Here a general approach is reported for preparing ultrathin PtNiM (M = Rh, Os, and Ir) nanowires (NWs) with excellent anti-CO-poisoning ability and high activity. Owing to their superior nanostructure and optimal electronic interaction, the ultrathin PtNiM NWs show enhanced electrocatalytic performance for both methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). The optimal PtNiRh NWs show mass activity of 1.72 A mg-1 and specific activity of 2.49 mA cm-2 for MOR, which are 3.17 and 2.79 times higher than those of Pt/C. In particular, the onset potentials of PtNiRh NWs for MOR and EOR shift down by about 65 and 85 mV compared with those of Pt/C. Density functional theory calculations further verify their high antipoison properties for MOR and EOR from both an electronic and energetic perspective. Facilitated by the introduction of Rh and Ni, the stable pinning of the Pt 5d band associated with electron-rich and depletion centers solves the dilemma between reactivity and anti-CO poisoning.

Ultrathin PtPd-Based Nanorings with Abundant Step Atoms Enhance Oxygen Catalysis.

The lack of highly active and stable catalysts with low Pt usage for the oxygen reduction reaction (ORR) is a major barrier in realizing fuel cell-driven transportation applications. A general colloidal chemistry method is demonstrated for making a series of ultrathin PtPdM (M = Co, Ni, Fe) nanorings (NRs) for greatly boosting ORR catalysis. Different from the traditional ultrathin nanosheets, the ultrathin PtPdM NRs herein have a high portion of step atoms on the edge, high Pt utilization efficiency, and strong ligand effect from M to Pt and fast mass transport of reactants to the NRs. These key features make them exhibit greatly enhanced electrocatalytic activity for the ORR and the oxygen evolution reaction (OER). Among all the PtPdM NRs, the PtPdCo shows the highest ORR mass and specific activities of 3.58 A mg-1 and 4.90 mA cm-2 at 0.9 V versus reversible hydrogen electrode (RHE), 23.9 and 24.5-fold larger than those of commercial Pt/C in alkaline electrolyte, respectively. The theoretical calculations reveal that the oxygen adsorption energy (E O ) can be optimized under the presence of step atoms exposed on the edge and ligand effect induced by Co. They are stable under ORR conditions with negligible changes after 30 000 cycles.