Local Dipole Modulation Toward High Fill Factor in Organic Solar Cells.

Dipole moment arrangement in organic semiconductors plays a critical role in affecting the intermolecular packing, determining optoelectronic properties and device performance. Here, to get the desired fill factor (FF) values in organic solar cells (OSCs), the local dipole of non-fullerene acceptors (NFAs) is modulated by changing the molecular asymmetries. Two NFAs, AA-1 and AA-2 are designed and synthesized, which have different substitutions of alkyl and alkoxyl groups.

The Role of Phase Mixing Degree in Promoting C-C Coupling in Electrochemical CO Reduction Reaction on Cu-based Catalysts.

Cu-based catalysts have been identified as the most promising candidates for generation of C2+ products in electrochemical CO reduction reaction. Defect engineering in catalysts is a widely employed strategy for promoting C-C coupling on Cu. However, comprehensive understanding of defect structure-to-activity relationship has not been obtained.

Infrared Spectroscopic Evidence of Enhanced Electrochemical CO Reduction and C-C Coupling on Oxide-Derived Copper.

The reaction mechanism of CO electroreduction on oxide-derived copper has not yet been unraveled even though high C Faradaic efficiencies are commonly observed on these surfaces. In this study, we aim to explore the effects of copper anodization on the adsorption of various CORR intermediates using surface-enhanced infrared absorption spectroscopy (SEIRAS) on metallic and mildly anodized copper thin films. The SEIRAS results show that the preoxidation process can significantly improve the overall CO reduction activity by (1) enhancing CO activation, (2) increasing CO uptake, and (3) promoting C-C coupling.

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis.

Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.

Synthesis of 2H/fcc-Heterophase AuCu Nanostructures for Highly Efficient Electrochemical CO Reduction at Industrial Current Densities.

Structural engineering of nanomaterials offers a promising way for developing high-performance catalysts toward catalysis. However, the delicate modulation of thermodynamically unfavorable nanostructures with unconventional phases still remains a challenge. Here, the synthesis of hierarchical AuCu nanostructures is reported with hexagonal close-packed (2H-type)/face-centered cubic (fcc) heterophase, high-index facets, planar defects (e.

MXene-Regulated Metal-Oxide Interfaces with Modified Intermediate Configurations Realizing Nearly 100% CO Electrocatalytic Conversion.

Electrocatalytic CO reduction via renewable electricity provides a sustainable way to produce valued chemicals, while it suffers from low activity and selectivity. Herein, we constructed a novel catalyst with unique Ti C T MXene-regulated Ag-ZnO interfaces, undercoordinated surface sites, as well as mesoporous nanostructures. The designed Ag-ZnO/Ti C T catalyst achieves an outstanding CO conversion performance of a nearly 100% CO Faraday efficiency with high partial current density of 22.

Sustainable and High-Rate Electrosynthesis of Nitrogen Fertilizer.

The conventional industrial production of nitrogen-containing fertilizers, such as urea and ammonia, relies heavily on energy-intensive processes, accounting for approximately 3 % of global annual CO emissions. Herein, we report a sustainable electrocatalytic approach that realizes direct and selective synthesis of urea and ammonia from co-reduction of CO and nitrates under ambient conditions. With the assistance of a copper (Cu)-based salphen organic catalyst, outstanding urea (3.

Seeded Synthesis of Hollow PdSn Intermetallic Nanomaterials for Highly Efficient Electrocatalytic Glycerol Oxidation.

Intermetallic nanomaterials have shown promising potential as high-performance catalysts in various catalytic reactions due to their unconventional crystal phases with ordered atomic arrangements. However, controlled synthesis of intermetallic nanomaterials with tunable crystal phases and unique hollow morphologies remains a challenge. Here, a seeded method is developed to synthesize hollow PdSn intermetallic nanoparticles (NPs) with two different intermetallic phases, that is, orthorhombic Pd Sn and monoclinic Pd Sn .

Steering CO electroreduction pathway toward ethanol via surface-bounded hydroxyl species-induced noncovalent interaction.

Selective electroreduction of carbon dioxide (CORR) into ethanol at an industrially relevant current density is highly desired. However, it is challenging because the competing ethylene production pathway is generally more thermodynamically favored. Herein, we achieve a selective and productive ethanol production over a porous CuO catalyst that presents a high ethanol Faradaic efficiency (FE) of 44.

Fe-N-C Boosts the Stability of Supported Platinum Nanoparticles for Fuel Cells.

The poor durability of Pt-based nanoparticles dispersed on carbon black is the challenge for the application of long-life polymer electrolyte fuel cells. Recent work suggests that Fe- and N-codoped carbon (Fe-N-C) might be a better support than conventional high-surface-area carbon. In this work, we find that the electrochemical surface area retention of Pt/Fe-N-C is much better than that of commercial Pt/C during potential cycling in both acidic and basic media.

Solution-Phase Synthesis of PdH Nanocubes with Enhanced Stability and Activity toward Formic Acid Oxidation.

Palladium is one of the few metals capable of forming hydrides, with the catalytic properties being dependent on the elemental composition and spatial distribution of H atoms in the lattice. Herein, we report a facile method for the complete transformation of Pd nanocubes into a stable phase made of PdH by treating them with aqueous hydrazine at a concentration as low as 9.2 mM.

Preparation of Au@Pd Core-Shell Nanorods with -2H- Heterophase for Highly Efficient Electrocatalytic Alcohol Oxidation.

Controlled construction of bimetallic nanostructures with a well-defined heterophase is of great significance for developing highly efficient nanocatalysts and investigating the structure-dependent catalytic performance. Here, a wet-chemical synthesis method is used to prepare Au@Pd core-shell nanorods with a unique -2H- heterophase (: face-centered cubic; 2H: hexagonal close-packed with a stacking sequence of "AB"). The obtained -2H- heterophase Au@Pd core-shell nanorods exhibit superior electrocatalytic ethanol oxidation performance with a mass activity as high as 6.

Maximizing the Catalytic Performance of Pd@Au Pd Nanocubes in H O Production by Reducing Shell Thickness to Increase Compositional Stability.

We report a simple route based upon seed-mediated growth to the synthesis of Pd@Au Pd (0.8≤x≤1) core-shell nanocubes. Benefiting from the well-defined {100} facets and an optimal Au/Pd ratio for the surface, the nanocubes bearing a shell made of Au Pd work as an efficient electrocatalyst toward H O production, with high selectivity of 93-100 % in the low-overpotential region of 0.

Highly Dispersive Cerium Atoms on Carbon Nanowires as Oxygen Reduction Reaction Electrocatalysts for Zn-Air Batteries.

Highly efficient noble-metal-free electrocatalysts for oxygen reduction reaction (ORR) are essential to reduce the costs of fuel cells and metal-air batteries. Herein, a single-atom Ce-N-C catalyst, constructed of atomically dispersed Ce anchored on N-doped porous carbon nanowires, is proposed to boost the ORR. This catalyst has a high Ce content of 8.

Recent Advances in Catalyst Structure and Composition Engineering Strategies for Regulating CO Electrochemical Reduction.

Electrochemical CO reduction has been recognized as a promising solution in tackling energy- and environment-related challenges of human society. In the past few years, the rapid development of advanced electrocatalysts has significantly improved the efficiency of this reaction and accelerated the practical applications of this technology. Herein, representative catalyst structures and composition engineering strategies in regulating the CO reduction selectivity and activity toward various products including carbon monoxide, formate, methane, methanol, ethylene, and ethanol are summarized.

Solid-State Synthesis of Highly Dispersed Nitrogen-Coordinated Single Iron Atom Electrocatalysts for Proton Exchange Membrane Fuel Cells.

Fe-N-C with atomically dispersed Fe single atoms is the most promising candidate to replace platinum for the oxygen reduction reaction (ORR) in fuel cells. However, the conventional synthesis procedures require quantities solvents and metal precursors, sluggish adsorption process, and tedious washing, resulting in limited metal doping and uneconomical for large-scale production. For the first time, FeO is adopted as the Fe precursor to derive abundant single Fe atoms dispersed on carbon surfaces.

Recent Advances in Electrocatalysts for Proton Exchange Membrane Fuel Cells and Alkaline Membrane Fuel Cells.

The rapid progress of proton exchange membrane fuel cells (PEMFCs) and alkaline exchange membrane fuel cells (AMFCs) has boosted the hydrogen economy concept via diverse energy applications in the past decades. For a holistic understanding of the development status of PEMFCs and AMFCs, recent advancements in electrocatalyst design and catalyst layer optimization, along with cell performance in terms of activity and durability in PEMFCs and AMFCs, are summarized here. The activity, stability, and fuel cell performance of different types of electrocatalysts for both oxygen reduction reaction and hydrogen oxidation reaction are discussed and compared.

Kinetically Controlled Synthesis of Pd-Cu Janus Nanocrystals with Enriched Surface Structures and Enhanced Catalytic Activities toward CO Reduction.

Bimetallic nanocrystals often outperform their monometallic counterparts in catalysis as a result of the electronic coupling and geometric effect arising from two different metals. Here we report a facile synthesis of Pd-Cu Janus nanocrystals with controlled shapes through site-selected growth by reducing the Cu(II) precursor with glucose in the presence of hexadecylamine and Pd icosahedral seeds. Specifically, at a slow reduction rate, the Cu atoms nucleate and grow from one vertex of the icosahedral seed to form a penta-twinned Janus nanocrystal in the shape of a pentagonal bipyramid or decahedron.

Advanced Electrocatalysts with Single-Metal-Atom Active Sites.

Electrocatalysts with single metal atoms as active sites have received increasing attention owing to their high atomic utilization efficiency and exotic catalytic activity and selectivity. This review aims to provide a comprehensive summary on the recent development of such single-atom electrocatalysts (SAECs) for various energy-conversion reactions. The discussion starts with an introduction of the different types of SAECs, followed by an overview of the synthetic methodologies to control the atomic dispersion of metal sites and atomically resolved characterization using state-of-the-art microscopic and spectroscopic techniques.

Controlling the Surface Oxidation of Cu Nanowires Improves Their Catalytic Selectivity and Stability toward C Products in CO Reduction.

Copper nanostructures are promising catalysts for the electrochemical reduction of CO because of their unique ability to produce a large proportion of multi-carbon products. Despite great progress, the selectivity and stability of such catalysts still need to be substantially improved. Here, we demonstrate that controlling the surface oxidation of Cu nanowires (CuNWs) can greatly improve their C selectivity and stability.

pH-Dependent Hydrogen and Water Binding Energies on Platinum Surfaces as Directly Probed through Surface-Enhanced Infrared Absorption Spectroscopy.

The origins of the pH-dependent kinetics of hydrogen evolution and oxidation reactions on Pt surfaces are unsolved dilemmas that have lasted for over half a century. In this study, surface-enhanced infrared absorption spectroscopy is applied to directly monitor the vibrational behaviors of adsorbed hydrogen atoms and interfacial water molecules on Pt surfaces in a wide pH window from 1.1 to 12.

A Spectroscopic Study of Electrochemical Nitrogen and Nitrate Reduction on Rhodium Surfaces.

Rh is a promising electrocatalyst for the nitrogen reduction reaction (NRR) given its suitable nitrogen-adsorption energy and low overpotential. However, the NRR pathway on Rh surfaces remains unknown. In this study, we employ surface-enhanced infrared-absorption spectroscopy (SEIRAS) and differential electrochemical mass spectrometry (DEMS) to study the reaction mechanism of NRR on Rh.

Tungsten Carbide and Cobalt Modified Nickel Nanoparticles Supported on Multiwall Carbon Nanotubes as Highly Efficient Electrocatalysts for Urea Oxidation in Alkaline Electrolyte.

The tungsten carbide and cobalt-modified Ni-based catalyst [Ni-Co-WC/multiwall carbon nanotubes (MWCNTs)], synthesized through a sequential impregnation method, was evaluated for the urea electrooxidation in alkaline electrolyte to reduce the overpotential and increase the current density simultaneously. The as-prepared Ni-Co-WC/MWCNTs catalyst was characterized using scanning electron microscopy-EDX, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Characterization results indicate that Ni, Co, and WC nanoparticles are uniformly distributed on the MWCNTs.

A Spectroscopic Study on the Nitrogen Electrochemical Reduction Reaction on Gold and Platinum Surfaces.

The electrochemical reduction of nitrogen to ammonia on Au-based catalysts showed a reasonably high Coulombic efficiency. The pathway of this promising reaction, however, is not clear partially due to the lack of information on reaction intermediates. Herein, surface-enhanced infrared absorption spectroscopy (SEIRAS) was employed to study the reaction mechanisms of nitrogen reduction on an Au thin film for the first time.