Small molecule-assisted synthesis of carbon supported platinum intermetallic fuel cell catalysts.

Supported ordered intermetallic compounds exhibit superior catalytic performance over their disordered alloy counterparts in diverse reactions. But the synthesis of intermetallic compounds catalysts often requires high-temperature annealing that leads to the sintering of metals into larger crystallites. Herein, we report a small molecule-assisted impregnation approach to realize the general synthesis of a family of intermetallic catalysts, consisting of 18 binary platinum intermetallic compounds supported on carbon blacks.

Intermetallic PtFe Electrocatalysts for the Oxygen Reduction Reaction: Ordering Degree-Dependent Performance.

Platinum-based atomically ordered alloys (i.e., intermetallic compounds) have distinct advantages over disordered solid solution counterparts in boosting the cathodic oxygen-reduction reaction (ORR) in proton-exchange-membrane fuel cells.

Precise fabrication of single-atom alloy co-catalyst with optimal charge state for enhanced photocatalysis.

While the surface charge state of co-catalysts plays a critical role for boosting photocatalysis, studies on surface charge regulation via their precise structure control remain extremely rare. Herein, metal-organic framework (MOF) stabilized bimetallic Pd@Pt nanoparticles, which feature adjustable Pt coordination environment and a controlled structure from core-shell to single-atom alloy (SAA), have been fabricated. Significantly, apart from the formation of a Mott-Schottky junction in a conventional way, we elucidate that Pt surface charge regulation can be alternatively achieved by changing its coordination environment and the structure of the Pd@Pt co-catalyst, where the charge between Pd and Pt is redistributed.

Synthesis of carbon-supported sub-2 nanometer bimetallic catalysts by strong metal-sulfur interaction.

Small-sized bimetallic nanoparticles that integrate the advantages of efficient exposure of the active metal surface and optimal geometric/electronic effects are of immense interest in the field of catalysis, yet there are few universal strategies for synthesizing such unique structures. Here, we report a novel method to synthesize sub-2 nm bimetallic nanoparticles (Pt-Co, Rh-Co, and Ir-Co) on mesoporous sulfur-doped carbon (S-C) supports. The approach is based on the strong chemical interaction between metals and sulfur atoms that are doped in the carbon matrix, which suppresses the metal aggregation at high temperature and thus ensures the formation of small-sized and well alloyed bimetallic nanoparticles.

Atomic Structural Evolution of Single-Layer Pt Clusters as Efficient Electrocatalysts.

The rational synthesis of single-layer noble metal directly anchored on support materials is an elusive target to accomplish for a long time. This paper reports well-defined single-layer Pt (Pt-SL) clusters anchored on ultrathin TiO nanosheets-as a new frontier in electrocatalysis. The structural evolution of Pt-SL/TiO via self-assembly of single Pt atoms (Pt-SA) is systematically recorded.

Sulfur stabilizing metal nanoclusters on carbon at high temperatures.

Supported metal nanoclusters consisting of several dozen atoms are highly attractive for heterogeneous catalysis with unique catalytic properties. However, the metal nanocluster catalysts face the challenges of thermal sintering and consequent deactivation owing to the loss of metal surface areas particularly in the applications of high-temperature reactions. Here, we report that sulfur-a documented poison reagent for metal catalysts-when doped in a carbon matrix can stabilize ~1 nanometer metal nanoclusters (Pt, Ru, Rh, Os, and Ir) at high temperatures up to 700 °C.

High-Temperature Synthesis of Small-Sized Pt/Nb Alloy Catalysts on Carbon Supports for Hydrothermal Reactions.

Catalytic biomass conversions are sustainable processes to produce value-added fuels and chemicals but need stable catalysts that can tolerate harsh hydrothermal conditions. Herein, we report a hydrothermally stable catalyst by alloying Pt with a high-melting-point metal Nb. The Pt/Nb alloy catalysts are prepared by H reduction at a high temperature of 900 °C with a high-surface-area carbon black support, which can suppress metal sintering at high temperatures and thus lead to small-sized alloyed Pt/Nb particles of only 2.

A sulfur-tethering synthesis strategy toward high-loading atomically dispersed noble metal catalysts.

Metals often exhibit robust catalytic activity and specific selectivity when downsized into subnanoscale clusters and even atomic dispersion owing to the high atom utilization and unique electronic properties. However, loading of atomically dispersed metal on solid supports with high metal contents for practical catalytic applications remains a synthetic bottleneck. Here, we report the use of mesoporous sulfur-doped carbons as supports to achieve high-loading atomically dispersed noble metal catalysts.

Hierarchically porous carbons as supports for fuel cell electrocatalysts with atomically dispersed Fe-N moieties.

The development of high-performance non-platinum group metal (non-PGM) catalysts for the oxygen reduction reaction (ORR) is still of significance in promoting the commercialization of proton exchange membrane fuel cells (PEMFCs). In this work, a "hierarchically porous carbon (HPC)-supporting" approach was developed to synthesize highly ORR active Fe-phenanthroline (Fe-phen) derived Fe-N -C catalysts. Compared to commercial carbon black supports, utilizing HPCs as carbon supports can not only prevent the formation of inactive iron nanoparticles during pyrolysis but also optimize the porous morphology of the catalysts, which eventually increases the amount of reactant-accessible and atomically dispersed Fe-N active sites.

Reversing the charge transfer between platinum and sulfur-doped carbon support for electrocatalytic hydrogen evolution.

Metal-support interaction is of great significance for catalysis as it can induce charge transfer between metal and support, tame electronic structure of supported metals, impact adsorption energy of reaction intermediates, and eventually change the catalytic performance. Here, we report the metal size-dependent charge transfer reversal, that is, electrons transfer from platinum single atoms to sulfur-doped carbons and the carbon supports conversely donate electrons to Pt when their size is expanded to ~1.5 nm cluster.

A metal-catalyzed thermal polymerization strategy toward atomically dispersed catalysts.

We report a general metal-catalyzed thermal polymerization strategy for the preparation of atomically dispersed catalysts that consist of isolated metal atoms (Fe, Co and Ni) hosted by a polymer-like carrier containing phenanthroline substructure. The prepared atomically dispersed cobalt catalysts exhibit high selectivity, activity, and reusability in catalyzing aromatic alkane oxidation.

Switching Co/N/C Catalysts for Heterogeneous Catalysis and Electrocatalysis by Controllable Pyrolysis of Cobalt Porphyrin.

Identifying the optimal synthetic and structural parameters in preparing pyrolyzed metal/nitrogen/carbon (M/N/C) materials is crucial for developing effective catalysts for many important catalytic processes. Here we report a group of mesoporous Co/N/C catalysts ranging from polymerized cobalt porphyrin to Co/N-doped carbons, which are prepared by pyrolysis of cobalt porphyrin using silica nanoparticles as templates at different temperatures, for boosting both heterogeneous catalysis and electrocatalysis. It is revealed that the polymerized cobalt porphyrin prepared at low temperature (500°C) is a polymer-like network with exclusive single-atom Co-N sites, and that the high-temperature-pyrolysis (>600°C) produces an electrically conductive Co/N-doped carbon, accompanied by part degradation of Co-N centers.