Interface modulation of twinned Pt Fe 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 Pt Fe nanodendrites(NDs)branched with two-dimensional(2 D)twinned nanoplates rather than conventional 1 D 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 Pt Fe NDs/C with amino-functionalized ionic liquids(ILs),we achieve an unprecedented mass activity of 3.15 A/mgPtat 0.9 V versus reversible hydrogen electrode(RHE)in the Pt Fe-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 Pt Fe NDs counterpart.The remarkable catalytic performance is attributed to a combination of several structural features,including 2 D 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.

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 Rh_4Pd_(40)Ag_(56)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^(à1)methanol,against a big decrease of almost 100%for commercial Pt.Even after 30,000 potential cycles with 1.0 mol L^(à1)methanol,Rh_4Pd_(40)Ag_(56)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.

Spiny Pd/PtFe core/shell nanotubes with rich high-index facets for efficient electrocatalysis

The performance of fuel-cell related electrocatalysis is highly dependent on the morphology,size and composition of a given catalyst.In terms of rational design of Pt-based catalyst,one-dimensional(1 D)ultrafine Pt alloy nanowires(NWs)are considered as a commendable model for enhanced catalysis on account of their favorable mass/charge transfer and structural durability.However,in order to achieve the noble metal catalysts in higher efficiency and lower cost,building high-index facets and shaping hollow interiors should be integrated into 1 D Pt alloy NWs,which has rarely been done so far.Here,we report the first synthesis of a class of spiny Pd/PtFe core/shell nanotubes(SPCNTs)constructed by cultivating PtFe alloy branches with rich high-index facets along the 1 D removable Pd supports,which is driven by the galvanic dissolution of Pd substrates concomitant with Stranski-Krastanov(S-K)growth of Pt and Fe,for achieving highly efficient fuel-cells-related electrocatalysis.This new catalyst can even deliver electrochemical active surface area(ECSA)of 62.7 m^(2)gPt^(-1),comparable to that of commercial carbonsupported Pt nanoparticles.With respect to oxygen reduction catalysis,the SPCNTs showcase the remarkable mass and specific activity of 2.71 A mg^(-1)and 4.32 mA cm^(-2),15.9 and 16.0 times higher than those of commercial Pt/C,respectively.Also,the catalysts exhibit extraordinary resistance to the activity decay and structural degradation during 50,000 potential cycles.Moreover,the SPCNTs serve as a category of efficient and stable catalysts towards anodic alcohol oxidation.

MOF derived Co3O4/N-doped carbon nanotubes hybrids as efficient catalysts for sensitive detection of H2O2 and glucose

Developing enzyme-free sensors with high sensitivity and selectivity for H2O2 and glucose is highly desirable for biological science.Especially,it is attractive to exploit noble-metal-free nanomaterials with large surface area and good conductivity as highly active and selective catalysts for molecular detection in enzyme-free sensors.Herein,we successfully fabricate hollow frameworks of Co3O4/N-doped carbon nanotubes(Co3O4/NCNTs)hybrids by the pyrolysis of metal-organic frameworks followed by calcination in the air.The as-prepared novel hollow Co3O4/NCNTs hybrids exhibit excellent electrochemical performance for H2O2 reduction in neutral solutions and glucose oxidation in alkaline solutions.As sensor electrode,the Co3O4/NCNTs show excellent non-enzymatic sensing ability towards H2O2 response with a sensitivity of 87.40μA(mmol/L)^-1 cm^-2,a linear range of 5.00μmol/L-11.00 mmol/L,and a detection limitation of 1μmol/L in H2O2 detection,and a good glucose detection performance with 5μmol/L.These excellent electrochemical performances endow the hollow Co3O4/NCNTs as promising alternative to enzymes in the biological applications.

Segmented Au/PtCo heterojunction nanowires for efficient formic acid oxidation catalysis

Exploring a new strategy for the removal of adsorbed CO (CO^(*)) on a Pt surface at a low potential is the key to achieving enhanced catalysis for the formic acid oxidation reaction (FAOR);however, the development of such a strategy remains a significant challenge. Herein, we report a class of Au/PtCo heterojunction nanowires (HNWs) as efficient electrocatalysts for accelerating the FAOR. This heterojunction structure and the induced Co alloying effects can facilitate formic acid adsorption/activation on Pt with high CO tolerance, generating the FAOR pathway from dehydration to dehydrogenation. The optimized Au_(23)/Pt_(63)Co_(14) HNWs showed the highest specific and mass activities of 11.7 mA cm^(−2)Pt and 6.42 A mg^(−1)Pt reported to date, respectively, which are considerably higher than those of commercial Pt/C. DFT calculations confirmed that the electron-rich Au segment enhances the electronic activity of the PtCo NWs, which not only allows the construction of a highly efficient electron transfer channel for the FAOR but also suppresses CO formation.