Steering acidic oxygen reduction selectivity of single-atom catalysts through the second sphere effect.

Natural enzymes feature distinctive second spheres near their active sites, leading to exquisite catalytic reactivity. However, incumbent synthetic strategies offer limited versatility in functionalizing the second spheres of heterogeneous catalysts. Here, we prepare an enzyme-mimetic single Co-N atom catalyst with an elaborately configured pendant amine group in the second sphere via 1,3-dipolar cycloaddition, which switches the oxygen reduction reaction selectivity from the 4e to the 2e pathway under acidic conditions.

Electronic perturbation of Cu nanowire surfaces with functionalized graphdiyne for enhanced CO reduction reaction.

Electronic perturbation of the surfaces of Cu catalysts is crucial for optimizing electrochemical CO reduction activity, yet still poses great challenges. Herein, nanostructured Cu nanowires (NW) with fine-tuned surface electronic structure are achieved via surface encapsulation with electron-withdrawing (-F) and -donating (-Me) group-functionalized graphdiynes (R-GDY, R = -F and -Me) and the resulting catalysts, denoted as R-GDY/Cu NW, display distinct CO reduction performances. electrochemical spectroscopy revealed that the *CO (a key intermediate of the CO reduction reaction) binding affinity and consequent *CO coverage positively correlate with the Cu surface oxidation state, leading to favorable C-C coupling on F-GDY/Cu NW over Me-GDY/Cu NW.

Metal-Free Wet Chemistry for the Fast Gram-Scale Synthesis of γ-Graphyne and its Derivatives.

γ-Graphyne (GY), an emerging carbon allotrope, is envisioned to offer various alluring properties and broad applicability. While significant progress has been made in the synthesis of GY over recent decades, its widespread application hinges on developing efficient, scalable, and accessible synthetic methods for the production of GY and its derivatives. Here we report a facile metal-free nucleophilic crosslinking method using wet chemistry for fast gram-scale production of GY and its derivatives.

Adaptive water oxidation catalysis on a carboxylate-sulfonate ligand with low onset potential.

A water oxidation catalyst Ru-bcs (bcs = 2,2'-bipyridine-6'-carboxylate-6-sulfonate) with a hybrid ligand was reported. Ru-bcs utilizes the electron-donating properties of carboxylate ligands and the on-demand coordination feature of sulfonate ligands to enable a low onset potential of 1.21 V NHE and a high TOF over 1000 s at pH 7.

Regulating Cu Oxidation State for Electrocatalytic CO Conversion into CO with Near-Unity Selectivity via Oxygen Spillover.

Cu-based catalysts are the most intensively studied in the field of electrocatalytic CO reduction reaction (CORR), demonstrating the capacity to yield diverse C and C products albeit with unsatisfactory selectivity. Manipulation of the oxidation state of Cu sites during CORR process proves advantageous in modulating the selectivity of productions, but poses a formidable challenge. Here, an oxygen spillover strategy is proposed to enhance the oxidation state of Cu during CORR by incorporating the oxygen donor SbO.

[2+1] Cycloadditions Modulate the Hydrophobicity of Ni-N Single-Atom Catalysts for Efficient CO Electroreduction.

Microenvironment regulation of M-N single-atom catalysts (SACs) is a promising way to tune their catalytic properties toward the electrochemical CO reduction reaction. However, strategies that can effectively introduce functional groups around the M-N sites through strong covalent bonding and under mild reaction conditions are highly desired. Taking the hydrophilic Ni-N SAC as a representative, we report herein a [2+1] cycloaddition reaction between Ni-N and in situ generated difluorocarbene (FC:), and enable the surface fluorocarbonation of Ni-N, resulting in the formation of a super-hydrophobic Ni-N-CF catalyst.

Dual Lewis Acid-Base Sites Regulate Silver-Copper Bimetallic Oxide Nanowires for Highly Selective Photoreduction of Carbon Dioxide to Methane.

Highly selective photoreduction of CO to valuable hydrocarbons is of great importance to achieving a carbon-neutral society. Precisely manipulating the formation of the Metal ⋅⋅⋅C=O⋅⋅⋅Metal (M ⋅⋅⋅C=O⋅⋅⋅M ) intermediate on the photocatalyst interface is the most critical step for regulating selectivity, while still a significant challenge. Herein, inspired by the polar electronic structure feature of CO molecule, we propose a strategy whereby the Lewis acid-base dual sites confined in a bimetallic catalyst surface are conducive to forming a M ⋅⋅⋅C=O⋅⋅⋅M intermediate precisely, which can promote selectivity to hydrocarbon formation.

Dynamic Surface Reconstruction of Amphoteric Metal (Zn, Al) Doped Cu O for Efficient Electrochemical CO Reduction to C Products.

The recognition of the surface reconstruction of the catalysts during electrochemical CO reduction (CO2RR) is essential for exploring and comprehending active sites. Although the superior performance of Cu-Zn bimetallic sites toward multicarbon C products has been established, the dynamic surface reconstruction has not been fully understood. Herein, Zn-doped Cu O nano-octahedrons are used to investigate the effect of the dynamic stability by the leaching and redeposition on CO2RR.

Second Sphere Effects Promote Formic Acid Dehydrogenation by a Single-Atom Gold Catalyst Supported on Amino-Substituted Graphdiyne.

Regulating the second sphere of homogeneous molecular catalysts is a common and effective method to boost their catalytic activities, while the second sphere effects have rarely been investigated for heterogeneous single-atom catalysts primarily due to the synthetic challenge for installing functional groups in their second spheres. Benefiting from the well-defined and readily tailorable structure of graphdiyne (GDY), an Au single-atom catalyst on amino-substituted GDY is constructed, where the amino group is located in the second sphere of the Au center. The Au atoms on amino-decorated GDY displayed superior activity for formic acid dehydrogenation compared with those on unfunctionalized GDY.

Defect-Engineered Cu-Based Nanomaterials for Efficient CO Reduction over Ultrawide Potential Window.

High conversion efficiency over a wide operating potential window is important for the practical application of CO reduction electrocatalysis, yet that remains a huge challenge in differentiating the competing CO reduction and H evolution. Here we introduce point defects (Sn doping) and planar defects (grain boundary) into the Cu substrate. This multidimensional defect integration strategy guides the fabrication of highly diluted SnCu polycrystal, which exhibits high Faradaic efficiencies (>95%) toward CO electroreduction over an ultrawide potential window (Δ = 1.

Electronic Perturbation of Copper Single-Atom CO Reduction Catalysts in a Molecular Way.

Fine-tuning electronic structures of single-atom catalysts (SACs) plays a crucial role in harnessing their catalytic activities, yet challenges remain at a molecular scale in a controlled fashion. By tailoring the structure of graphdiyne (GDY) with electron-withdrawing/-donating groups, we show herein the electronic perturbation of Cu single-atom CO reduction catalysts in a molecular way. The elaborately introduced functional groups (-F, -H and -OMe) can regulate the valance state of Cu , which is found to be directly scaled with the selectivity of the electrochemical CO -to-CH conversion.

Single-Site Heterogeneous Organometallic Ir Catalysts Embedded on Graphdiyne: Structural Manipulation Beyond the Carbon Support.

Accurate control over the coordination circumstances of single-atom catalysts (SACs) is decisive to their intrinsic activity. Here, two single-site heterogeneous organometallic catalysts (SHOCs), Cp*Ir-L/GDY (L = OH and Cl ; Cp* = pentamethylcyclopentadienyl), with the fine-tuned local coordination and electronic structure of Ir sites, are constructed by anchoring Cp*Ir complexes on graphdiyne (GDY) matrix via a one-pot procedure. The spectroscopic studies and theoretical calculations indicate that the Ir atoms in Cp*Ir-Cl/GDY and Cp*Ir-OH/GDY have a much higher oxidation state than Ir in the SAC Ir/GDY.

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting.

Langmuir adsorption model is a classic physical-chemical adsorption model and is widely used to describe the monolayer adsorption behavior at the material interface in environmental chemistry. Traditional adsorption dynamic modeling solely considered the surface physiochemical interaction between the adsorbent and adsorbate. The surface reaction dynamics resulting from the heterogeneous surface and intrinsic electronic structure of absorbents were rarely considered within the reported adsorption experiments.

Hydroxylamine mediated Fenton-like interfacial reaction dynamics on sea urchin-like catalyst derived from spent LiFePO battery.

Herein, we converted spent LiFePO battery to the sea urchin-like material (SULM) with a highly efficient and environment-friendly method, which can contribute to building a zero-waste city. With SULM as a Fenton-like catalyst, a highly-efficient degradation process was realized for organic pollutants with interface and solution synergistic effect. In our SULM+NHOH+HO Fenton-like system, NHOH can effectively promote the interface iron (Fe(Ⅲ)/Fe(Ⅱ)) and solution iron (Fe(Ⅲ)/Fe(Ⅱ)) redox cycle, thus promoting the generation of reactive oxygen species (ROS).

BiO/BiO Nanoheterojunction for Highly Efficient Electrocatalytic CO Reduction to Formate.

Heterostructure engineering plays a vital role in regulating the material interface, thus boosting the electron transportation pathway in advanced catalysis. Herein, a novel BiO/BiO heterojunction catalyst was synthesized via a molten alkali-assisted dealumination strategy and exhibited rich structural dynamics for an electrocatalytic CO reduction reaction (ECORR). By coupling in situ X-ray diffraction and Raman spectroscopy measurements, we found that the as-synthesized BiO/BiO heterostructure can be transformed into a novel Bi/BiO Mott-Schottky heterostructure, leading to enhanced adsorption performance for CO and *OCHO intermediates.

Sacrificial W Facilitates Self-Reconstruction with Abundant Active Sites for Water Oxidation.

Water oxidation is an important reaction for multiple renewable energy conversion and storage-related devices and technologies. High-performance and stable electrocatalysts for the oxygen evolution reaction (OER) are urgently required. Bimetallic (oxy)hydroxides have been widely used in alkaline OER as electrocatalysts, but their activity is still not satisfactory due to insufficient active sites.

Interfacial engineering of CuFeS quantum dots via platinum decoration with enhanced Cr(VI) reduction dynamics under UV-Vis-NIR radiation.

Configuring reactive and stable catalytic interfaces is crucial to design efficient photocatalysts for Cr(VI) reduction. Herein, via the platinum decoration approach based on interfacial engineering, we developed an effective catalytic interface within novel semiconducting chalcopyrite quantum dots (Pt/CuFeS QDs). Benefiting from the catalytic merits of the Pt modulated interfacial structure and electronic structure, Pt/CuFeS QDs show a broader light absorption capability extending to near-infrared radiation (NIR) range with superior carriers separation performance and faster charge transfer efficiency, which delivers a three-folder faster photocatalytic Cr(VI) reduction efficiency comparing to the original CuFeS QDs.

An amide-based second coordination sphere promotes the dimer pathway of Mn-catalyzed CO-to-CO reduction at low overpotential.

The [-Mn(bpy)(CO)Br] complex is capable of catalyzing the electrochemical reduction of CO to CO with high selectivity, moderate activity and large overpotential. Several attempts have been made to lower the overpotential and to enhance the catalytic activity of this complex by manipulating the second-coordination sphere of manganese and using relatively stronger acids to promote the pathway. We report herein that the complex [-Mn(bpy-CONHMe)(CO)(MeCN)] ([]; bpy-CONHMe = -methyl-(2,2'-bipyridine)-6-carboxamide) as a pre-catalyst could catalyze the electrochemical reduction of CO to CO with low overpotential and high activity and selectivity.

Surface Functionalization of a γ-Graphyne-like Carbon Material via Click Chemistry.

Surface functionalization of carbon materials is of interest in many research fields, such as electrocatalysis, interfacial engineering, and supercapacitors. As an emerging carbon material, γ-graphyne has attracted broad attention. Herein, we report that the surface functionalization of a γ-graphyne-like carbon material (γ-G1) is achieved by immobilizing functional groups via the click chemistry.

Efficient Iridium Catalysts for Formic Acid Dehydrogenation: Investigating the Electronic Effect on the Elementary β-Hydride Elimination and Hydrogen Formation Steps.

We report herein a series of Cp*Ir complexes containing a rigid 8-aminoquinolinesulfonamide moiety as highly efficient catalysts for the dehydrogenation of formic acid (FA). The complex [Cp*Ir(L)Cl] (HL = -(quinolin-8-yl)benzenesulfonamide) displayed a high turnover frequency (TOF) of 2.97 × 10 h and a good stability (>100 h) at 60 °C.

From Ru-bda to Ru-bds: a step forward to highly efficient molecular water oxidation electrocatalysts under acidic and neutral conditions.

Significant advances during the past decades in the design and studies of Ru complexes with polypyridine ligands have led to the great development of molecular water oxidation catalysts and understanding on the O-O bond formation mechanisms. Here we report a Ru-based molecular water oxidation catalyst [Ru(bds)(pic)] (Ru-bds; bds = 2,2'-bipyridine-6,6'-disulfonate) containing a tetradentate, dianionic sulfonate ligand at the equatorial position and two 4-picoline ligands at the axial positions. This Ru-bds catalyst electrochemically catalyzes water oxidation with turnover frequencies (TOF) of 160 and 12,900 s under acidic and neutral conditions respectively, showing much better performance than the state-of-art Ru-bda catalyst.

Regulating kinetics and thermodynamics of electrochemical nitrogen reduction with metal single-atom catalysts in a pressurized electrolyser.

Using renewable electricity to synthesize ammonia from nitrogen paves a sustainable route to making value-added chemicals but yet requires further advances in electrocatalyst development and device integration. By engineering both electrocatalyst and electrolyzer to simultaneously regulate chemical kinetics and thermodynamic driving forces of the electrocatalytic nitrogen reduction reaction (ENRR), we report herein stereoconfinement-induced densely populated metal single atoms (Rh, Ru, Co) on graphdiyne (GDY) matrix (formulated as M SA/GDY) and realized a boosted ENRR activity in a pressurized reaction system. Remarkably, under the pressurized environment, the hydrogen evolution reaction of M SA/GDY was effectively suppressed and the desired ENRR activity was strongly amplificated.

Size-Dependent Activity and Selectivity of Atomic-Level Copper Nanoclusters during CO/CO Electroreduction.

As a favorite descriptor, the size effect of Cu-based catalysts has been regularly utilized for activity and selectivity regulation toward CO /CO electroreduction reactions (CO /CORR). However, little progress has been made in regulating the size of Cu nanoclusters at the atomic level. Herein, the size-gradient Cu catalysts from single atoms (SAs) to subnanometric clusters (SCs, 0.