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The unveiling of MOF growth mechanism is hampered by the lack of fundamental knowledge about the very early stage of nucleation, especially the form and ratio of molecular species in the solution for crystal growth. Herein, we report the detection of growth species for a series of MOFs with mono-linker, Cu-MOF-2-BDC and Cu-MOF-2-NDC, and two linkers, MTV-MOF-2-(C4H4)x, by high resolution ESI-MS, where a large variety of Cu-containing species are identified unambiguously. The solvent molecules such as H2O, methanol and DMF participate in the formation of these species, other than ethanol. Furthermore, in the growth solution of MTV-MOF-2-(C4H4)x, growth species containing two different organic linkers are observed. The feeding ratio is not the only factor controlling the distribution of growth species for MTV-MOFs, but also the solvent involves in coordination, an aspect usually overlooked previously.

A novel iron-hydrogen battery system, whose Fe3+/Fe2+ cathode circumvents slowly dynamic oxygen reduction reaction and anode is fed with clean and cordial hydrogen, is systematically investigated. The maximum discharge power density of the iron-hydrogen battery reaches to 96.0 mW/cm2 under the room temperature. The capacity reaches to 17.2 Ah/L and the coulombic and energy efficiency are achieved to 99% and 86%, respectively, during the galvanostatic charge-discharge test. Moreover, stable cycling test is observed for more than 240 h and 100 cycles with the iron sulfate in the sulfuric acid solutions. It is found that air plasma treatment onto the cathode carbon paper can generate the oxygen-containing groups and increase the hydrophilic pores proportion to ca. 40%, enlarging nearly 6-fold effective diffusion coefficient and improving the mass transfer in the battery performance. The simple iron-hydrogen energy storage battery design offers us a new strategy for the large-scale energy storage and hydrogen involved economy.

The ordered membrane electrode assembly (MEA) is currently the frontier research field of proton exchange membrane fuel cells (PEMFCs). The ordered MEA is effective in increasing the utilization of...

The nature of many highly efficient catalytic reactions catalyzed by metallocofactors is inspiring. Herein, the concept of metal cofactor was utilized in the in situ fabrication of multiple metal and heteroatom self-doped porous carbonaceous electrocatalysts. The sustainable biomass legume root nodules that contain nitrogenase were used as single precursors, and the specific surface area of the as-prepared catalyst could reach 1835 m2 g−1 by the activation of ZnCl2 during high-temperature pyrolysis processes. The self-doped biomass-derived catalyst exhibits an outstanding oxygen reduction reaction (ORR) electrocatalytic performance with half-wave potentials (E1/2) of 0.723 V and 0.868 V (vs. RHE) in 0.1 M HClO4 and 0.1 M KOH solution, respectively. It is worth noting that E1/2 of the catalyst even outperforms 25 mV to that of Pt/C (E1/2 = 0.843 V) in alkaline electrolytes. This performance is also markedly better than that of most other reference catalysts, which is based on codoped additional transition metals or heteroatoms with biomass-derived carbonaceous materials. The catalyst also delivers promising fuel cell performance in both low-temperature air-breathing polymer electrolyte membrane fuel cells (PEMFCs) and Zn–air batteries. The role of Mo atoms from the iron-molybdenum cofactor in the as-prepared biomass-derived catalyst toward ORRs is discussed herein. This study is expected to inspire exploration and design of appropriate doping structures and compositions to develop highly active and renewable biomass-derived catalysts in diverse application fields.

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...

Nanobubble is a rising research field, which attracts more and more attentions due to its potential applications in medical science, catalysis, electrochemistry and etc. To better implement these applications, it is urgent to understand one of the most important mechanisms of nanobubbles, the evolution. However, few attentions have been paid in this aspect because of the methodology difficulties. Here we successfully used dark-field microscopy to study the evolution process of single nanobubbles generated from formic acid dehydrogenation on single Pd-Ag nanoplates. We found some of the nanobubbles in this system can exhibit three distinct states representing different sizes, which can transform among each other. These transitions are not direct but through some intermediate states. Further kinetic analysis reveals complicated mechanisms behind the evolution of single nanobubbles. The results acquired from this study can be applicable to nanobubble systems in general and provide insights into the understanding of mechanisms affecting the stability of nanobubbles and their applications.

Five new sesquiterpenoids, alashanoids O-S (1-5), along with three known analogs (6-8) were isolated from the peeled stems of Syringa pinnatifolia. Their structures were elucidated by analysis of extensive spectroscopic data including ESI-MS, 1D, 2D NMR. The absolute configurations were determined by comparing its experimental and calculated electronic circular dichroism, calculated OR, calculated NMR, and single crystal X-ray diffraction data analysis. Compounds 1 and 2 belong to the seco-humulane type and possess a rare 13-membered oxygen heterocycle framework, and 3-5 belong to eremophilane-type. Compounds 1, 2, and 5 showed inhibitory effects against NO production in LPS-induced RAW264.7 macrophage cells with its IC

Smaller volume/weight and higher output power/energy density are always the goals of electrochemistry energy devices. Here, a simple strategy is proposed to prepare an integrated gas diffusion electrode (GDE) with high conductivity through skin electroplating. The skin electroplating is the combination of magnetron sputtering and spatial confinement electroplating. The electroplated metal obtained by skin electroplating is uniformly, continuously, and tightly attached to the surface of carbon paper like a layer of skin. Uniform and continuous electroplating metal layer endows the integrated electrode excellent conductivity with the square resistance as low as 27 mΩ sq

A gas diffusion layer (GDL) is one of the essential components of a membrane electrode assembly (MEA), which is the core of proton exchange membrane fuel cells (PEMFCs). However, with the rapid development of PEMFCs, current commercial GDLs are encountering or will encounter many problems, such as complex preparation processes, very high preparation temperature (2000 °C), very high thickness, and high cost. In this research, we developed a simple three-step method to produce a novel flexible, low thickness, low-cost, and high performance GDL by a simple process with low preparation temperatures, low energy consumption and low equipment cost. The three-step method mainly includes creating pores, coating with a microporous layer and heat treatment; it uses only carbon nanotube (CNT) films, CNT powder and polytetrafluoroethylene (PTFE) as the raw materials. The temperature of heat treatment in this research is only 350 °C, which is much lower than 2000 °C required for the preparation of commercial GDLs. The new GDL has many advantages, such as very low thickness (less than 40 μm, only about 1/6 of that of commercial GDL), high flexibility (bending radius < 0.17 mm), low cost and large size (200 mm × 200 mm). Moreover, the overall thickness of the MEA prepared with the new GDL was less than 90 μm, which was only about 1/3 of that of the MEA made with a commercial GDL. Outstandingly, the volume-specific power density of the air-breathing PEMFC made with the new GDL dramatically increased to 15 600 W L−1, and the weight-specific power density reached 9660 W kg−1. It is estimated that the volume-specific power density of the PEMFC stack has potential to be improved by more than 60% by simply replacing the commercial GDL with the new GDL reported in this work. Therefore, this work not only develops a new method for GDL preparation but also provides a new GDL with comprehensive advantages, which is necessary for the next generation of PEMFCs.

Proton exchange membrane fuel cells (PEMFCs) have potential applications in electric vehicles, laptops, and power stations. The catalyst layers in a membrane electrode assembly (MEA) are the core locations in PEMFCs in which to convert the chemical energy of fuels to electrical energy. For a catalyst layer with high performance, it must possess three fast transfer ways to transfer mass (reactants and products), electrons (e−) and protons (H+) quickly and simultaneously. In this work, we greatly improved the performance and lifetime of a fuel cell by constructing these three fast transfer pathways based on a well-ordered and cone-shaped Nafion array with a very high density (5.7 × 108 cones per cm2) using an anodic aluminum oxide (AAO) template. To build a fast pathway for electron transfer, well-dispersed graphene nanosheets were further filled into the Nafion array. After a series of efforts based on the above, the performance of the fuel cell with a cone array as an anode reached 1240 mW cm−2, which is 2.5 times higher than that without an array. Since Pt loading was as low as 17.6 μg cm−2, the mass specific power of Pt was as high as 70.5 kW gPt−1. Consequently, the Pt loading successfully reached the U.S. DOE 2020 target at the anode side, i.e. 25 μg cm−2. In addition, the lifetime of the PEMFC with the cone array is at least 300 h, which is much longer than the 150 h for a PEMFC without an array. Therefore, this work fully exhibits the great potential advantages of using an ordered Nafion array, and is promising to promote the development of the next generation of MEA for use in PEMFCs.

Flexible electrochemical power sources are attracting increasing attentions for their unique advantages like flexibility, shape diversity, light weight and excellent mechanical properties. In this research, we discover that the current collector can dramatically affect the performance of flexible electrochemical power sources with large size. For flexible air-breathing proton exchange membrane fuel cell (PEMFC), the performance could have more than 8 times increase by only adjusting the directions of current collectors. The different performances of different current collection types are mainly attributed to the diverse lengths of the electron transfer pathways. In addition, the conductivity of current collector can dramatically affect the capability of flexible PEMFCs with large-size. The flexible PEMFCs with thicker carbon nanotube membrane as current collector (low electric resistance) show higher ability. A mathematic model is successfully built in this work to further understand the performance. Moreover, the model and simulation are also applicable to other flexible power sources, such as flexible Li-ion battery and supercapacitor.

Gas-generating catalysis is important to many energy-related research fields, such as photocatalytic water splitting, water electrolysis, etc. The technique of single-nanoparticle catalysis is an effective way to search for highly active nanocatalysts and elucidate the reaction mechanism. However, gas-generating catalysis remains difficult to investigate at the single-nanoparticle level because product gases, such as H2 and O2, are difficult to detect on an individual nanoparticle. Here, we successfully find that nanobubbles can be used to study the gas-generating catalysis, i.e., H2 generation from formic acid dehydrogenation on a single Pd–Ag nanoplate, with a high time resolution (50 ms) via dark-field microscopy. The research reveals that the nanobubble evolution process includes nucleation time and lifetime. The nucleation rate of nanobubbles is proportional to the catalytic activity of a single nanocatalyst. The relationship between the catalytic activity and the nucleation rate is quantitatively de...

Ir complexes are important homogeneous catalysts for formic acid (FA) dehydrogenation. This paper reports that the activity of Ir complexes can be greatly improved through the activation by trace amounts of oxygen. After activation the activity of the heterodinuclear Ir–Ru catalyst increased 18-fold whereas for the mononuclear catalyst a 23-fold increase was observed. Oxygen is the key factor for the activation. But an excessive concentration of oxygen has a negative effect on the activity. There is an optimal concentration of H2O2 for the activation of Ir complex catalysts in HCOOH dehydrogenation. A very low concentration of oxygen (2.4 × 10–6 M) is needed for the activation of the heterodinuclear Ir–Ru catalyst while the mononuclear catalyst requires the presence of oxygen in a much higher concentration (290 × 10–6 M). From the results of the study it can be inferred that the activation of complex catalysts is due to the interplay of chemical and structural changes. These findings may be helpful in the attempts to improve the catalytic activity of homogeneous catalysts, which are widely used in formic acid dehydrogenation, CO2 reduction and in other processes. In addition, this paper indicates that iridium complexes are excellent catalysts for the direct synthesis of H2O2 from the H2 and O2.

Formic acid (FA) dehydrogenation has attracted a lot of attentions since it is a convenient method for H 2 production. In this work, we designed a self-supporting fuel cell system, in which H 2 from FA is supplied into the fuel cell, and the exhaust heat from the fuel cell supported the FA dehydrogenation. In order to realize the system, we synthesized a highly active and selective homogeneous catalyst IrCp*Cl 2 bpym for FA dehydrogenation. The turnover frequency (TOF) of the catalyst for FA dehydrogenation is as high as 7150 h −1 at 50 °C, and is up to 144,000 h −1 at 90 °C. The catalyst also shows excellent catalytic stability for FA dehydrogenation after several cycles of test. The conversion ratio of FA can achieve 93.2%, and no carbon monoxide is detected in the evolved gas. Therefore, the evolved gas could be applied in the proton exchange membrane fuel cell (PEMFC) directly. This is a potential technology for hydrogen storage and generation. The power density of the PEMFC driven by the evolved gas could approximate to that using pure hydrogen.

A homogeneous catalyst [Cp*Rh(NH 3 )(H 2 O) 2 ] 3+ has been found for the clean conversion of methanol and water to hydrogen and carbon dioxide. The simple and easily available reaction steps can circumvent the formation of CO, therefore, making it possible to avoid inactivating catalysts and contaminating the hydrogen fuel. Different from conventional reforming method for hydrogen production, no additional alkaline or organic substances are required in this method. Valuable hydrogen can be obtained under ambient pressure at 70 °C, corresponding TOF is 83.2 h −1 . This is an unprecedented success in reforming methanol to hydrogen. Effects of reaction conditions, such as reaction temperature, initial methanol concentration and the initial pH value of buffer solution on the hydrogen evolution are all systematically investigated. In a certain range, higher reaction temperature will accelerate reaction rate. The slightly acidic condition is conducive to rapid hydrogen production. These findings are of great significance to the present establishment of the carbon-neutral methanol economy.

One-dimensional (1D) and two-dimensional (2D) nanomaterials usually show diverse catalytic activities at different locations. For a particular location, the local reaction activity could be too fast to be measured by super-resolution microscopy (SRM). To solve this problem, this research uses a large array of polydimethylsiloxane (PDMS) microchambers to resolve the site-specific activity on a single gold nanoplate with micrometer resolution, in situ and in real time. This research presents a general method to screen the catalytic activity distribution on single nanomaterials, even if the local activity is up to TOF = 5.9 × 105 s–1, the adsorption time of the fluorescent molecule is short, and fluorescence quenching occurs on the nanomaterials. This research reveals that the site-specific activities of different regions on a single gold nanoplate follows the trend corner > edge > flat facet. This research also reveals that the site-specific activities of the flat facet and corner regions are not dependent ...

Concerns about the depletion of fossil fuel reserves and environmental pollution make hydrogen an attractive alternative energy source. Here, we first describe a catalytic reaction system that produces H2 from glucose using a homogeneous catalyst [(p-cymene)Ru(NH3)]Cl2 with the maximum TOF = 719 h−1 at 98 °C and an initial pH = 0.5.

As a promising hydrogen storage medium methanol has many advantages such as a high hydrogen content (12.5 wt%) and low-cost. However, conventional methanol–water reforming methods usually require a high temperature (>200 °C). In this research, we successfully designed an effective strategy to fully convert methanol to hydrogen for at least 1900 min (∼32 h) at near-room temperature. The strategy involves two main procedures, which are CH3OH → HCOOH → H2 and CH3OH → NADH → H2. HCOOH and the reduced form of nicotinamide adenine dinucleotide (NADH) are simultaneously produced through the dehydrogenation of methanol by the cooperation of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Subsequently, HCOOH is converted to H2 by a new iridium polymer complex catalyst and an enzyme mimic is used to convert NADH to H2 and nicotinamide adenine dinucleotide (NAD+). NAD+ can then be reconverted to NADH by repeating the dehydrogenation of methanol. This strategy and the catalysts invented in this research can also be applied to hydrogen production from other small organic molecules (e.g. ethanol) or biomass (e.g. glucose), and thus will have a high impact on hydrogen storage and applications.

Nanosynthesis is the basis of nanotechnology and its applications. It is necessary to understand the growth mechanism of nanoparticles and the functions of growth factors. An effective way to study the synthesis is at the single nanoparticle level. This study reports a single nanoparticle spectrometer, which is based on a commercial dark-field microscopy and a group of narrowband filters. This spectrometer has many advantages, such as high light transparency (35%-75%), low cost (

Single molecule catalysis is very powerful in revealing catalytic mechanism at the single molecule level. But fluorescent molecule is always necessary to take part into the catalysis directly in previous research. In order to study the single molecule electro-catalysis of non-fluorescent molecule (SMECNFM) on nano-catalyst, we couple the SMECNFM with a single molecule fluorescence reaction. A certain number of fluorescent molecules will be generated and detected when the SMECNFM happens. Through this method, we can detect the electro-oxidation reaction of one HCOONa molecule. The stability of Pt nano-catalyst supported on active carbon is studied at the single molecule level by this method. This paper also provides a general way to make ultra-sensitive sensor, and to study the SMECNFM for the molecules, such as formic acid, hydrogen, oxygen, etc. , on single nanoparticle.

Enzymes often show catalytic allostery in which reactions occurring at different sites communicate cooperatively over distances of up to a few nanometres. Whether such effects can occur with non-biological nanocatalysts remains unclear, even though these nanocatalysts can undergo restructuring and molecules can diffuse over catalyst surfaces. Here we report that phenomenologically similar, but mechanistically distinct, cooperative effects indeed exist for nanocatalysts. Using spatiotemporally resolved single-molecule catalysis imaging, we find that catalytic reactions on a single Pd or Au nanocatalyst can communicate with each other, probably via hopping of positively charged holes on the catalyst surface, over ~102 nanometres and with a temporal memory of ~101 to 102 seconds, giving rise to positive cooperativity among its surface active sites. Similar communication is also observed between individual nanocatalysts, however it operates via a molecular diffusion mechanism involving negatively charged product molecules, and its communication distance is many micrometres. Generalization of these long-range intra- and interparticle catalytic communication mechanisms may introduce a novel conceptual framework for understanding nanoscale catalysis.

This review discusses the latest advances in using single-molecule microscopy of fluorogenic reactions to examine and understand the spatiotemporal catalytic behaviors of single metal nanoparticles of various shapes including pseudospheres, nanorods, and nanoplates. Real-time single-turnover kinetics reveal size-, catalysis-, and metal-dependent temporal activity fluctuations of single pseudospherical nanoparticles (

High-throughput and quantitative screening of catalyst activity is crucial for guiding the work cycles of catalyst improvements and optimizations. For nanoparticle catalysts, their inherent heterogeneity makes it desirable to screen them at the single-particle level. Here, we report a single-molecule fluorescence microscopy approach that can screen the activity quantitatively of a large number of catalyst particles in parallel at the single-particle level and with subdiffraction spatial resolution. It can identify directly high activity catalyst particles and resolve subpopulations in mixtures of catalysts. It is readily scalable and broadly applicable to heterogeneous catalysts. Using ensemble measurements to establish activity correlations between different reactions, we further show that this approach can be extended to assess catalysts in reactions that do not involve fluorescent molecules. Coupled with high-throughput catalyst preparation and high-resolution structural/compositional analysis, this sc...

A series of Mo-doped ZnO photocatalysts with different Mo-dopant concentrations have been prepared by a grinding-calcination method. The structure of these photocatalysts was characterized by a variety of methods, including N2 physical adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, photoluminescence (PL) emission spectroscopy, and UV-vis diffuse reflectance spectroscopy (DRS). It was found that Mo6+ could enter into the crystal lattice of ZnO due to the radius of Mo6+ (0.065 nm) being smaller than that of Zn2+ (0.083 nm). XRD results indicated that Mo6+ suppressed the growth of ZnO crystals. The FT-IR spectroscopy results showed that the ZnO with 2 wt.% Mo-doping has a higher level of surface hydroxyl groups than pure ZnO. PL spectroscopy indicated that ZnO with 2 wt.% Mo-doping also exhibited the largest reduction in the intensity of the emission peak at 390 nm caused by the recombination of photogenerated hole-electron pairs. The activities of the Mo-doped ZnO photocatalysts were investigated in the photocatalytic degradation of acid orange II under UV light (λ = 365 nm) irradiation. It was found that ZnO with 2 wt.% Mo-doping showed much higher photocatalytic activity and stability than pure ZnO. The high photocatalytic performance of the Mo-doped ZnO can be attributed to a great improvement in the surface properties of ZnO, higher crystallinity and lower recombination rate of photogenerated hole-electron (e−/h+) pairs. Moreover, the undoped Mo species may exist in the form of MoO3 and form MoO3/ZnO heterojunctions which further favors the separation of e−/h+ pairs.

Using single-molecule microscopy of fluorogenic reactions we studied Pt nanoparticle catalysis at single-particle, single-turnover resolution for two reactions: one an oxidative N-deacetylation and the other a reductive N-deoxygenation. These Pt nanoparticles show distinct catalytic kinetics in these two reactions: one following noncompetitive reactant adsorption and the other following competitive reactant adsorption. In both reactions, single nanoparticles exhibit temporal activity fluctuations attributable to dominantly spontaneous surface restructuring. Depending on the reaction sequence, single Pt nanoparticles may or may not show activity correlations in catalyzing both reactions, reflecting the structure insensitivity of the N-deacetylation reaction and the structure sensitivity of the N-deoxygenation reaction.

A novel PdAu bimetallic catalyst with a PdAu@Au core−shell nanostructure supported on carbon was facilely synthesized by a simultaneous reduction method without using any stabilizer. The structure was characterized by cyclic voltammetry, X-ray diffraction, transmission electron microscopy (TEM), and high-angle annular dark-field scanning TEM combining with X-ray energy-dispersive spectroscopy. The obtained catalyst was applied in hydrogen generation from formic acid decomposition. Results show that the structured bimetallic catalyst possesses superior activity, high selectivity, and stability at low temperature. The reforming gas from formic acid decomposition contains only 30 ppm of CO and can be used directly in fuel cell.

We report a single-molecule fluorescence study of electrocatalysis by single-walled carbon nanotubes (SWNTs) at single-reaction resolution. Applying super-resolution optical imaging, we find that the electrocatalysis occurs at discrete, nanometer-dimension sites on SWNTs. Single-molecule kinetic analysis leads to an electrocatalytic mechanism, allowing quantification of the reactivity and heterogeneity of individual reactive sites. Combined with conductivity measurements, this approach will be powerful to interrogate how the electronic structure of SWNTs affects the electrocatalytic interfacial charge transfer, a process fundamental to photoelectrochemical cells.

Shape-controlled metal nanocrystals are a new generation of nanoscale catalysts. Depending on their shapes, these nanocrystals exhibit various surface facets, and the assignments of their surface facets have routinely been used to rationalize or predict their catalytic activity in a variety of chemical transformations. Recently we discovered that for 1-dimensional (1D) nanocrystals (Au nanorods), the catalytic activity is not constant along the same side facets of single nanorods but rather differs significantly and further shows a gradient along its length, which we attributed to an underlying gradient of surface defect density resulting from their linear decay in growth rate during synthesis (Nat. Nanotechnol.2012, 7, 237-241). Here we report that this behavior also extends to 2D nanocrystals, even for a different catalytic reaction. By using super-resolution fluorescence microscopy to map out the locations of catalytic events within individual triangular and hexagonal Au nanoplates in correlation with scanning electron microscopy, we find that the catalytic activity within the flat {111} surface facet of a Au nanoplate exhibits a 2D radial gradient from the center toward the edges. We propose that this activity gradient results from a growth-dependent surface defect distribution. We also quantify the site-specific activity at different regions within a nanoplate: The corner regions have the highest activity, followed by the edge regions and then the flat surface facets. These discoveries highlight the spatial complexity of catalytic activity at the nanoscale as well as the interplay amid nanocrystal growth, morphology, and surface defects in determining nanocatalyst properties.

This tutorial review covers recent developments in using single-molecule fluorescence microscopy to study nanoscale catalysis. The single-molecule approach enables following catalytic and electrocatalytic reactions on nanocatalysts, including metal nanoparticles and carbon nanotubes, at single-reaction temporal resolution and nanometer spatial precision. Real-time, in situ, multiplexed measurements are readily achievable under ambient solution conditions. These studies provide unprecedented insights into catalytic mechanism, reactivity, selectivity, and dynamics in spite of the inhomogeneity and temporal variations of catalyst structures. Prospects, generality, and limitations of the single-molecule fluorescence approach for studying nanocatalysis are also discussed.

Nanoparticles are important catalysts for petroleum processing, energy conversion, and pollutant removal. As compared to their bulk counterparts, their often superior or new catalytic properties result from their nanometer size, which gives them increased surface-to-volume ratios and chemical potentials. The size of nanoparticles is thus pivotal for their catalytic properties. Here, we use single-molecule fluorescence microscopy to study the size-dependent catalytic activity and dynamics of spherical Au-nanoparticles under ambient solution conditions. By monitoring the catalysis of individual Au-nanoparticles of three different sizes in real time with single-turnover resolution, we observe clear size-dependent activities in both the catalytic product formation reaction and the product dissociation reaction. Within a model of classical thermodynamics, these size-dependent activities of Au-nanoparticles can be accounted for by the changes in the adsorption free energies of the substrate resazurin and the product resorufin because of the nanosize effect. We also observe size-dependent differential selectivity of the Au-nanoparticles between two parallel product dissociation pathways, with larger nanoparticles less selective between the two pathways. The particle size also strongly influences the surface-restructuring-coupled catalytic dynamics; both the catalysis-induced and the spontaneous dynamic surface restructuring occur more readily for smaller Au-nanoparticles due to their higher surface energies. Using a simple thermodynamic model, we analyze the catalysis- and size-dependent dynamic surface restructuring quantitatively; the results provide estimates on the activation energies and time scales of spontaneous dynamic surface restructuring that are fundamental to heterogeneous catalysis in both the nano- and the macro-scale. This study further exemplifies the power of the single-molecule approach in probing the intricate workings of nanoscale catalysts.

The in situ heterogeneous catalytic reaction of formic acid decomposition was applied as a ‘reaction template’ in the synthesis of porous Pd black. The obtained porous Pd black was characterized by transmission electron microscopy, electrochemical measurements and x-ray photoelectron spectroscopy. It was found that the porous Pd black had a high electrochemical active surface area of about 40:2 m 2 g 1 and a clean surface. It could be used directly as a catalyst in many fields such as fuel cells. (Some figures may appear in colour only in the online journal)

Pd-Au/C and Pd-Ag/C were found to have a unique characteristic of evolving high-quality hydrogen dramatically and steadily from the catalyzed decomposition of liquid formic acid at convenient temperature, and further this was improved by the addition of CeO(2)(H(2)O)(x).