Strong Interaction between Titanium Carbonitride Embedded in Mesoporous Carbon Nanofibers and Pt Enables Durable Oxygen Reduction.

Platinum (Pt) supported on high surface area carbon has been the most widely used electrocatalyst in proton exchange membrane fuel cell (PEMFC). However, conventional carbon supports are susceptible to corrosion at high potentials, leading to severe degradation of electrochemical performance. In this work, titanium carbonitride embedded in mesoporous carbon nanofibers (m-TiCN NFs) are reported as a promising alternative to address this issue.

Atomically Precise Single-Site Catalysts via Exsolution in a Polyoxometalate-Metal-Organic-Framework Architecture.

Single-site catalysts (SSCs) achieve a high catalytic performance through atomically dispersed active sites. A challenge facing the development of SSCs is aggregation of active catalytic species. Reducing the loading of these sites to very low levels is a common strategy to mitigate aggregation and sintering; however, this limits the tools that can be used to characterize the SSCs.

Pyrazine-linked Iron-coordinated Tetrapyrrole Conjugated Organic Polymer Catalyst with Spatially Proximate Donor-Acceptor Pairs for Oxygen Reduction in Fuel Cells.

Nitrogen-coordinated iron (Fe-N ) materials represent the most promising non-noble electrocatalysts for the cathodic oxygen reduction reaction (ORR) of fuel cells. However, molecular-level structure design of Fe-N electrocatalyst remains a great challenge. In this study, we develop a novel Fe-N conjugated organic polymer (COP) electrocatalyst, which allows for precise design of the Fe-N structure, leading to unprecedented ORR performance.

Hierarchical palladium catalyst for highly active and stable water oxidation in acidic media.

Acidic water electrolysis is of great importance for boosting the development of renewable energy. However, it severely suffers from the trade-off between high activity and long lifespan for oxygen evolution catalysts on the anode side. This is because the sluggish kinetics of oxygen evolution reaction necessitates the application of a high overpotential to achieve considerable current, which inevitably drives the catalysts far away from their thermodynamic equilibrium states.

Synthetic Access to a Framework-Stabilized and Fully Sulfided Analogue of an Anderson Polyoxometalate that is Catalytically Competent for Reduction Reactions.

Polyoxometalates (POMs) featuring 7, 12, 18, or more redox-accessible transition metal ions are ubiquitous as selective catalysts, especially for oxidation reactions. The corresponding synthetic and catalytic chemistry of stable, discrete, capping-ligand-free polythiometalates (PTMs), which could be especially attractive for reduction reactions, is much less well developed. Among the challenges are the propensity of PTMs to agglomerate and the tendency for agglomeration to block reactant access of catalyst active sites.

Mesoporous multi-shelled hollow resin nanospheres with ultralow thermal conductivity.

Hollow nanostructures exhibit enclosed or semi-enclosed spaces inside and the consequent features of restricting molecular motion, which is crucial for intrinsic physicochemical properties. Herein, we developed a new configuration of hollow nanostructures with more than three layers of shells and simultaneously integrated mesopores on every shell. The novel interior configuration expresses the characteristics of periodic interfaces and abundant mesopores.

Directional Manipulation of Electron Transfer by Energy Level Engineering for Efficient Cathodic Oxygen Reduction.

Electron transfer plays an important role in determining the energy conversion efficiency of energy devices. Nitrogen-coordinated single metal sites (M-N) materials as electrocatalysts have exhibited great potential in devices. However, there are still great difficulties in how to directionally manipulate electron transfer in M-N catalysts for higher efficiency.

Isomer of linker for NU-1000 yields a new she-type, catalytic, and hierarchically porous, Zr-based metal-organic framework.

The well-known MOF (metal-organic framework) linker tetrakis(p-benzoate)pyrene (TBAPy) lacks steric hindrance between its benzoates. Changing the 1,3,6,8-siting of benzoates in TBAPy to 4,5,9,10-siting introduces substantial steric hindrance and, in turn, enables the synthesis of a new hierarchically porous, she-type MOF Zr(μ-O)(μ-OH)(CHCOO)(COO)(TBAPy-2) (NU-601), where TBAPy-2 is the 4,5,9,10 isomer of TBAPy. NU-601 shows high catalytic activity for degradative hydrolysis of a simulant for G-type fluoro-phosphorus nerve agents.

Surface Immobilization of Transition Metal Ions on Nitrogen-Doped Graphene Realizing High-Efficient and Selective CO Reduction.

Electrochemical conversion of CO to value-added chemicals using renewable electricity provides a promising way to mitigate both global warming and the energy crisis. Here, a facile ion-adsorption strategy is reported to construct highly active graphene-based catalysts for CO reduction to CO. The isolated transition metal cyclam-like moieties formed upon ion adsorption are found to contribute to the observed improvements.

Exclusive Ni-N Sites Realize Near-Unity CO Selectivity for Electrochemical CO Reduction.

Electrochemical reduction of carbon dioxide (CO) to value-added carbon products is a promising approach to reduce CO levels and mitigate the energy crisis. However, poor product selectivity is still a major obstacle to the development of CO reduction. Here we demonstrate exclusive Ni-N sites through a topo-chemical transformation strategy, bringing unprecedentedly high activity and selectivity for CO reduction.

Engineering the electronic structure of two-dimensional subnanopore nanosheets using molecular titanium-oxide incorporation for enhanced photocatalytic activity.

Engineering the electronic structure of two-dimensional (2D) nanomaterials endows unique physical and chemical properties. Although developed modification strategies have significantly expanded the applications of 2D nanomaterials, exploring new strategies to regulate the electronic structure of 2D nanomaterials is also expected. Herein, we highlight a new strategy to engineer the electronic structure of 2D subnanoporous nanomaterials.

Single-Atom Pt as Co-Catalyst for Enhanced Photocatalytic H2 Evolution.

Isolated single-atom platinum (Pt) embedded in the sub-nanoporosity of 2D g-C3 N4 as a new form of co-catalyst is reported. The highly stable single-atom co-catalyst maximizes the atom efficiency and alters the surface trap states of g-C3 N4 , leading to significantly enhanced photocatalytic H2 evolution activity, 8.6 times higher than that of Pt nanoparticles and up to 50 times that for bare g-C3 N4 .

Molecular co-catalyst accelerating hole transfer for enhanced photocatalytic H2 evolution.

In artificial photocatalysis, sluggish kinetics of hole transfer and the resulting high-charge recombination rate have been the Achilles' heel of photocatalytic conversion efficiency. Here we demonstrate water-soluble molecules as co-catalysts to accelerate hole transfer for improved photocatalytic H2 evolution activity. Trifluoroacetic acid (TFA), by virtue of its reversible redox couple TFA·/TFA(-), serves as a homogeneous co-catalyst that not only maximizes the contact areas between co-catalysts and reactants but also greatly promotes hole transfer.

Graphene/sulfur hybrid nanosheets from a space-confined "sauna" reaction for high-performance lithium-sulfur batteries.

A space-confined "sauna" reaction system is introduced for the simultaneous reduction and functionalization of graphene oxide to unique graphene-sulfur hybrid nanosheets, in which thin layers of amorphous sulfur are tightly anchored on the graphene sheet via strong chemical bonding. Upon being used as the cathode material in lithium-sulfur batteries, the as-synthesized composite shows an excellent electrochemical performance.

Ultrahigh energy density realized by a single-layer β-Co(OH)2 all-solid-state asymmetric supercapacitor.

A conceptually new all-solid-state asymmetric supercapacitor based on atomically thin sheets is presented which offers the opportunity to optimize supercapacitor properties on an atomic level. As a prototype, β-Co(OH)2 single layers with five-atoms layer thickness were synthesized through an oriented-attachment strategy. The increased density-of-states and 100 % exposed hydrogen atoms endow the β-Co(OH)2 single-layers-based electrode with a large capacitance of 2028 F g(-1) .

Spatial location engineering of oxygen vacancies for optimized photocatalytic H2 evolution activity.

Enhanced H2 evolution efficiency is achieved via manipulating the spatial location of oxygen vacancies in niobates. The ultrathin K4 Nb6O17 nanosheets which are rich in surface oxygen vacancies show enhanced optical absorption and band gap narrowing. Meanwhile, the fast charge separation effectively reduces the probability of hole-electron recombination, enabling 20 times hydrogen evolution rate compared with the defect-free bulk counterpart.

In-plane coassembly route to atomically thick inorganic-organic hybrid nanosheets.

Control over the anisotropic assembly of small building blocks into organized structures is considered an effective way to design organic nanosheets and atomically thick inorganic nanosheets with nonlayered structure. However, there is still no available route so far to control the assembly of inorganic and organic building blocks into a flattened hybrid nanosheet with atomic thickness. Herein, we highlight for the first time a universal in-plane coassembly process for the design and synthesis of transition-metal chalcogenide-alkylamine inorganic-organic hybrid nanosheets with atomic thickness.

CuInSe2 ultrathin nanoplatelets: novel self-sacrificial template-directed synthesis and application for flexible photodetectors.

Non-layered chalcopyrite-type CuInSe(2) nanoplatelets, with thickness down to 2 nm, have been synthesized for the first time. The ultrathin nanoplatelets are of benefit for low-cost and high performance flexible photodetectors.

New aspects of size-dependent metal-insulator transition in synthetic single-domain monoclinic vanadium dioxide nanocrystals.

Nanoscale materials with size smaller than the characteristic domain size could simplify the domain structure and uncover the intrinsic properties in detail. Herein, a ultrafast open space calcination pathway is first put forward to synthesize high-quality single-domain VO(2)(M) nanocrystals and an in situ variable-temperature IR spectroscopy is first proposed to identify the size-dependent MIT behaviors in VO(2)(M) below single-domain size. The variable-temperature IR spectroscopy clearly reveals that these single-domain VO(2)(M) nanocrystals exhibit new size-dependent MIT behaviors, while the IR analysis further suggests that the size-related defect density and scattering efficiency could be used to account for their novel size-dependent MIT behaviors.