Hybridization of Defective Tin Disulfide Nanosheets and Silver Nanowires Enables Efficient Electrochemical Reduction of CO2 into Formate and Syngas

Integrating the defect engineering and conductivity promotion represents a promising way to improve the performance of CO₂ electrochemical reduction. Herein, the hybridized composite of defective SnS₂ nanosheets and Ag nanowires is developed as an efficient catalyst for the production of formate and syngas toward CO₂ electrochemical reduction. The Schottky barrier in Ag‐SnS₂ hybrid nanosheets is negligible due to the similar Fermi level of SnS₂ nanosheets and Ag nanowires. Accordingly, the free electrons of Ag nanowires participate in the electronic transport of SnS₂ nanosheets, and thus give rise to a 5.5‐fold larger carrier density of Ag‐SnS₂ hybrid nanosheets than that of SnS₂ nanosheets. In CO₂ electrochemical reduction, the Ag‐SnS₂ hybrid nanosheets display 38.8 mA cm^?2 of geometrical current density at –1.0 V vs reversible hydrogen electrode, including 23.3 mA cm^?2 for formate and 15.5 mA cm^?2 for syngas with the CO/H₂ ratio of 1:1. A mechanistic study reveals that the abundant defect sites and carrier density not only promote the conductivity of the electrocatalyst, but also increase the binding strength for CO₂, which account for the efficient CO₂ reduction.     

Preparation and tunable photoluminescence of alloyed CdS<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> nanorods

Ternary alloys of CdS _x Se_1−x nanorods have been synthesized by the thermal treatment of Cd²⁺ dispersed polyethylene glycol 2000 gel (PEG2000) with ethylenediamine solution of sulfur and selenium in a sealed system at 180 °C for 24 h, during which the proportion between S and Se in the nanorods was controlled by the ratios of every starting material to each other. The alloyed ternary CdS _x Se_1−x nanorods are highly crystalline without any other phase. The optical property these nanorods could be manipulated by modulating the composition of S and Se.     

Novel Bi-Doped Amorphous SnOx Nanoshells for Efficient Electrochemical CO2 Reduction into Formate at Low Overpotentials

Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO₂ reduction. Herein, the first synthesis of homogeneous Sn_1−xBi_x alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnO_x shells for efficient CO₂ reduction is reported. The Bi-SnO_x nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnO_x nanoshells derived from Sn_0.80Bi_0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm⁻² and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H₂ and CO.     

Synthesis of CdSxSe1−x nanorods via a solvothermal route

CdS_xSe_1−x (0 ≤ x ≤ 1) nanorods with diameter of 10–20 nm and length up to 100–150 nm were successfully synthesized via a solvothermal route. It was found that the CdS_xSe_1−x nanorods could be obtained at a temperature as low as 120 °C and the size distribution of the nanorods did not change with temperature and composition. A thin layer of CdS was detected beside the CdS_xSe_1−x products and proposed to act as crystal seeds in the incorporating process of CdS_xSe_1−x, thus decreasing the reaction temperature effectively. The exploration of ultraviolet–visible (UV–vis) absorption properties of the CdS_xSe_1−x samples confirmed that the band gaps of the CdS_xSe_1−x nanocrystals could be easily tuned via the control of composition, which may indicate its wide application in many fields.     

Structural electrical and optical properties of CdSxSe1 − x films

Complete solid solutions of CdS_xSe_{1 ? x} over the range0 ? x ? 1 were grown by pyrolytic decomposition. The films had a predominant hexagonal structure with lattice constants varying linearly with composition. At an illumination level of 10 mW cm^-2, the decay time for CdSe was 1.2 ms and decreased with increased in the background illumination, the lifetime of the majority carriers being 1 ms.     

Abundant Ce3+ Ions in Au‐CeOx Nanosheets to Enhance CO2 Electroreduction Performance

The electroreduction of CO₂ to CO provides a potential way to solve the environmental problems caused by excess fossil fuel utilization. Loading transition metals on metal oxides is an efficient strategy for CO₂ electroreduction as well as for reducing metal usage. However, it needs a great potential to overcome the energy barrier to increase CO selectivity. This paper describes how 8.7 wt% gold nanoparticles (NPs) loaded on CeO_x nanosheets (NSs) with high Ce³⁺ concentration effectively decrease the overpotential for CO₂ electroreduction. The 3.6 nm gold NPs on CeO_x NSs containing 47.3% Ce³⁺ achieve CO faradaic efficiency of 90.1% at ?0.5 V in 0.1 m KHCO₃ solution. Furthermore, the CO₂ electroreduction activity shows a strong relationship with the fractions of Ce³⁺ on Au‐CeO_x NSs, which has never been reported. In situ surface‐enhanced infrared absorption spectroscopy shows that Au‐CeO_x NSs with high Ce³⁺ concentration promote CO₂ activation and *COOH formation. Theoretical calculations also indicate that the improved performance is attributed to the enhanced *COOH formation on Au‐CeO_x NSs with high Ce³⁺ fraction.     

Strategic Atomic Layer Deposition and Electrospinning of Cobalt Sulfide/Nitride Composite as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Reported herein is comprehensive study of a highly active and stable cobalt catalyst for overall water splitting. This composite SFCNF/Co_1?xS@CoN, consisting of S‐doped flexible carbon nanofiber (SFCNF) matrix, Co_1?xS nanoparticles, and CoN coatings, is prepared by integration of electrospinning and atomic layer deposition (ALD) technique. Representative results include the following: 1) ultrathin CoN layer is deposited by ALD on the surface of flexible substrate without any sacrifice of SFCNF and Co_1?xS; 2) the composite exhibits strong electrocatalytic activity in both acidic and basic solutions. The overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are 20 and 180 mV, respectively, at a current density of 10 mA cm^?2 in basic medium. A small Tafel slope of 54.4 mV dec^?1 is observed in 0.5 m H₂SO₄ electrolyte; 3) tested as overall water splitting electrode, the composite records a current density of 10 mA cm^?2 at a relative low cell voltage of 1.58 V and long‐term stability for 20 h at a current density of up to 50 mA cm^?2. The superior performance for overall water splitting is probably attributed to the synergistic effect of Co_1?xS and ALD CoN. Specifically, implementation of ALD can be extended to innovate nanostructured materials for overall water splitting and even other renewable energy aspects.     

Hierarchical 3D Oxygenated Cobalt Molybdenum Selenide Nanosheets as Robust Trifunctional Catalyst for Water Splitting and Zinc–Air Batteries

The development of hierarchical nanostructures with highly active and durable multifunctional catalysts has a new significance in the context of new energy technologies of water splitting and metal–air batteries. Herein, a strategy is demonstrated to construct a 3D hierarchical oxygenated cobalt molybdenum selenide (O‐Co_1?xMo_xSe₂) series with attractive nanoarchitectures, which are fabricated by a simple and cost‐effective hydrothermal process followed by an exclusive ion‐exchange process. Owing to its highly electroactive sites with numerous nanoporous networks and plentiful oxygen vacancies, the optimal O‐Co_0.5Mo_0.5Se₂ could catalyze the hydrogen evolution reaction and oxygen evolution reaction effectively with a low overpotential of ≈102 and 189 mV, at a current density of 10 mA cm^?2, respectively, and exceptional durability. Most importantly, the O‐Co_0.5Mo_0.5Se₂||O‐Co_0.5Mo_0.5Se₂ water splitting device only entails a voltage of ≈1.53 V at a current density of 10 mA cm^?2, which is much better than benchmark Pt/C||RuO₂ (≈1.56 V). Furthermore, O‐Co_0.5Mo_0.5Se₂ air cathode‐based zinc–air batteries exhibit an excellent power density of 120.28 mW cm^?2 and exceptional cycling stability for 60 h, superior to those of state‐of‐art Pt/C+RuO₂ pair‐based zinc–air batteries. The present study provides a strategy to design hierarchical 3D oxygenated bimetallic selenide‐based multifunctional catalysts for energy conversion and storage systems.     

The Role of Interfacial Water in CO2 Electrolysis over Ni-N-C Catalyst in a Membrane Electrode Assembly Electrolyzer

CO₂ electrolysis is a promising route for achieving net-zero emission through decarbonization. To realize CO₂ electrolysis toward practical application, beyond catalyst structures, it is also critical to rationally manipulate catalyst microenvironments such as the water at the electrode/electrolyte interface. Here, the role of interfacial water in CO₂ electrolysis over Ni-N-C catalyst modified with different polymers is investigated. Benefiting from a hydrophilic electrode/electrolyte interface, the Ni-N-C catalyst modified with quaternary ammonia poly(N-methyl-piperidine-co-p-terphenyl) shows a Faradaic efficiency of 95% and a partial current density of 665 mA cm⁻² for CO production in an alkaline membrane electrode assembly electrolyzer. A scale-up demonstration using a 100 cm² electrolyzer achieves a CO production rate of 514 mL min⁻¹ at a current of 80 A. In-situ microscopy and spectroscopy measurements indicate that the hydrophilic interface significantly promotes the formation of the *COOH intermediate, rationalizing the high CO₂ electrolysis performance.     

Nickel–Cobalt Diselenide 3D Mesoporous Nanosheet Networks Supported on Ni Foam: An All‐pH Highly Efficient Integrated Electrocatalyst for Hydrogen Evolution

Novel 3D Ni_1?x Co_x Se₂ mesoporous nanosheet networks with tunable stoichiometry are successfully synthesized on Ni foam (Ni_1?x Co_x Se₂ MNSN/NF with x ranging from 0 to 0.35). The collective effects of special morphological design and electronic structure engineering enable the integrated electrocatalyst to have very high activity for hydrogen evolution reaction (HER) and excellent stability in a wide pH range. Ni_0.89Co_0.11Se₂ MNSN/NF is revealed to exhibit an overpotential (η₁₀) of 85 mV at ?10 mA cm^?2 in alkaline medium (pH 14) and η₁₀ of 52 mV in acidic solution (pH 0), which are the best among all selenide‐based electrocatalysts reported thus far. In particular, it is shown for the first time that the catalyst can work efficiently in neutral solution (pH 7) with a record η₁₀ of 82 mV for all noble metal‐free electrocatalysts ever reported. Based on theoretical calculations, it is further verified that the advanced all‐pH HER activity of Ni_0.89Co_0.11Se₂ is originated from the enhanced adsorption of both H⁺ and H₂O induced by the substitutional doping of cobalt at an optimal level. It is believed that the present work provides a valuable route for the design and synthesis of inexpensive and efficient all‐pH HER electrocatalysts.     

Lattice-Strain Engineering of Homogeneous NiS0.5Se0.5 Core–Shell Nanostructure as a Highly Efficient and Robust Electrocatalyst for Overall Water Splitting

Developing highly-efficient non-noble-metal electrocatalysts for water splitting is crucial for the development of clean and reversible hydrogen energy. Introducing lattice strain is an effective strategy to develop efficient electrocatalysts. However, lattice strain is typically co-created with heterostructure, vacancy, or substrate effects, which complicate the identification of the strain-activity correlation. Herein, a series of lattice-strained homogeneous NiS_xSe_1−x nanosheets@nanorods hybrids are designed and synthesized by a facile strategy. The NiS_0.5Se_0.5 with ≈2.7% lattice strain exhibits outstanding activity for hydrogen and oxygen evolution reaction (HER/OER), affording low overpotentials of 70 and 257 mV at 10 mA cm⁻², respectively, as well as excellent long-term durability even at a large current density of 100 mA cm⁻² (300 h), significantly superior to other benchmarks and the precious metal catalysts. Experimental and theoretical calculation results reveal that the generated lattice strain decreases the metal d-orbital overlap, leading to a narrower bandwidth and a closer d-band center toward the Fermi level. Thus, NiS_0.5Se_0.5 possesses favorable H* adsorption kinetics for HER and lower energy barriers for OER. This work provides a new insight to regulate the lattice strain of advanced catalyst materials and further improve the performance of energy conversion technologies.     

Rational Design of FeNi Bimetal Modified Covalent Organic Frameworks for Photoconversion of Anthropogenic CO2 into Widely Tunable Syngas

Direct photoconversion of low‐concentration CO₂ into a widely tunable syngas (i.e., CO/H₂ mixture) provides a feasible outlet for the high value‐added utilization of anthropogenic CO₂. However, in the low‐concentration CO₂ photoreduction system, it remains a huge challenge to screen appropriate catalysts for efficient CO and H₂ production, respectively, and provide a facile parameter to tune the CO/H₂ ratio in a wide range. Herein, by engineering the metal sites on the covalent organic frameworks matrix, low‐concentration CO₂ can be efficiently photoconverted into tunable syngas, whose CO/H₂ ratio (1:19–9:1) is obviously wider than reported systems. Experiments and density functional theory calculations indicate that Fe sites serve as the H₂ evolution sites due to the much stronger binding affinity to H₂O, while Ni sites act as the CO production sites for the higher affinity to CO₂. Notably, the widely tunable syngas can also be produced over other Fe/Ni‐based bimetal catalysts, regardless of their structures and supporting materials, confirming the significant role of the metal sites in regulating the selectivity of CO₂ photoreduction and providing a modular design strategy for syngas production.     

Anionic Se‐Substitution toward High‐Performance CuS1−xSex Nanosheet Cathode for Rechargeable Magnesium Batteries

Rechargeable magnesium batteries (rMBs) are promising as the most ideal further energy storage systems but lack competent cathode materials due to sluggish redox reaction kinetics. Herein, developed is an anionic Se‐substitution strategy to improve the rate capability and the cycling stability of 2D CuS_1?xSe_x nanosheet cathodes through an efficient microwave‐induced heating method. The optimized CuS_1?xSe_x (X = 0.2) nanosheet cathode can exhibit high reversible capacity of 268.5 mAh g^?1 at 20 mA g^?1 and good cycling stability (140.4 mAh g^?1 at 300 mA g^?1 upon 100 cycles). Moreover, the CuS_1?xSe_x (X = 0.2) nanosheet cathode can deliver remarkable rate capability with a reversible capacity of 119.2 mAh g^?1 at 500 mA g^?1, much higher than the 21.7 mAh g^?1 of pristine CuS nanosheets. The superior electrochemical performance can be ascribed to the enhanced reaction kinetics, enriched cation storage active sites, and shortened ion diffusion pathway of the CuS_1?xSe_x nanosheet. Therefore, tuning anionic chemical composition demonstrates an effective strategy to develop novel cathode materials for rMBs.     

Highly efficient orange–red electroluminescence from a single layer MEH-PPV-POSS:CdS0.75Se0.25 hybrid PLED

In this study, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] end capped with polyhedral oligomeric silsesquioxanes (MEH-PPV-POSS): cadmium sulfide selenide quantum dots (CdS_0.75Se_0.25 QDs) nanocomposites based OLEDs were fabricated. By the addition of CdS_0.75Se_0.25 QDs into the polymer active layer, a considerable enhancement was observed in terms of hole and electron injection in devices. Additionally, the presence of QDs reduced the interchain interaction of polymer that resulted in narrower electroluminescence (EL) spectrum. The device structure of ITO/PEDOT: PSS/MEH-PPV-POSS: 25 wt% CdS_0.75Se_0.25/Ca (40 nm)/Al demonstrated the best performance with a brightness of 8672 cd/m² at 10 V, current efficiency of 2.5 cd/A at 8 V, and an EQE of 0.55% at 150 mA/cm².     

Syngas production via coal char-CO2 fluidized bed gasification and the effect on the performance of LSCFN//LSGM//LSCFN solid oxide fuel cell

Fluidized bed reactor is widely used in coal char-CO_2 gasification. In this work, the production of syngas by using a fluidized bed gasification technique was first investigated and then the effect of the produced syngas on the performance of the solid oxide fuel cell with a configuration of La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)//La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17)O_(3-δ)//La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)(LSCFN//LSGM//LSCFN)was studied. During the syngas production, we found that the volume fraction of CO increased with the increment of gasification temperature, and it reached a maximum value of 88.8%, corresponding to a composition of 0.76% H_2, 88.8% CO, and 10.44% CO_2, when the ratio of oxygen mass flow rate to that of coal char(MO2/Mchar) increased to 0.29. In the following utilization of the produced syngas in solid oxide fuel cells, it was found that the increasing CO volume fraction in the syngas results in a gradual increase of the peak power density of the LSCFN//LSGM//LSCFN cell. The maximum peak power density of 410 m W/cm~2 was achieved for the syngas produced at 0.29 of M_(O2)/M_(char). In the stability test, the cell voltage decreased by 4% at a constant current density of 0.475 A/cm~2 after 54 h when fueled with the syngas with the composition of 0.76% H2, 88.8% CO, and 10.44% CO_2.It reveals that a carbon deposition with the content of 13.66% in the anode is attributed to the cell performance degradation.     

Reductive Transformation of Layered‐Double‐Hydroxide Nanosheets to Fe‐Based Heterostructures for Efficient Visible‐Light Photocatalytic Hydrogenation of CO

Conversion of syngas (CO, H₂) to hydrocarbons, commonly known as the Fischer–Tropsch (FT) synthesis, represents a fundamental pillar in today's chemical industry and is typically carried out under technically demanding conditions (1–3 MPa, 300–400 °C). Photocatalysis using sunlight offers an alternative and potentially more sustainable approach for the transformation of small molecules (H₂O, CO, CO₂, N₂, etc.) to high‐valuable products, including hydrocarbons. Herein, a novel series of Fe‐based heterostructured photocatalysts (Fe‐x) is successfully fabricated via H₂ reduction of ZnFeAl‐layered double hydroxide (LDH) nanosheets at temperatures (x) in the range 300–650 °C. At a reduction temperature of 500 °C, the heterostructured photocatalyst formed (Fe‐500) consists of Fe⁰ and FeO_x nanoparticles supported by ZnO and amorphous Al₂O₃. Fe‐500 demonstrates remarkable CO hydrogenation performance with very high initial selectivities toward hydrocarbons (89%) and especially light olefins (42%), and a very low selectivity towards CO₂ (11%). The intimate and abundant interfacial contacts between metallic Fe⁰ and FeO_x in the Fe‐500 photocatalyst underpins its outstanding photocatalytic performance. The photocatalytic production of high‐value light olefins with suppressed CO₂ selectivity from CO hydrogenation is demonstrated here.     

Sol-gel preparation of CdS x Se1−x solid solution microcrystal-doped glasses

CdS _x Se_1–x solid solution microcrystal-doped glasses with a significant quantum-sized effect were prepared by the sol-gel process. Gels synthesized by the hydrolysis of complex solution of Si(OC₂H₅)₄, Cd(CH₃COO)₂·2H₂O and selenium were treated in H₂S and hydrogen gas atmospheres to form CdS _x Se_1–x solid solution crystals, whose compositions were determined from the X-ray diffraction and Raman scattering spectra. Sulphur in CdS crystals is substituted for selenium by heating in hydrogen gas, and its content decreases with increasing temperature. On the other hand, the sulphur content increases on reacting the CdSe crystalprecipitated glasses with H₂S gas. The optical absorption spectra are shifted towards the red as the crystal size increases, and the gap energy is reciprocally proportional to the square of the crystal size.     

Highly Active,Durable Ultrathin MoTe2 Layers for the Electroreduction of CO2 to CH4

The electroreduction of CO₂ to CH₄ is a highly desirable, challenging research topic. In this study, an electrocatalytic system comprising ultrathin MoTe₂ layers and an ionic liquid electrolyte for the reduction of CO₂ to methane is reported, efficiently affording methane with a faradaic efficiency of 83 ± 3% (similar to the best Cu‐based catalysts reported thus far) and a durable activity of greater than 45 h at a relatively high current density of 25.6 mA cm^?2 (?1.0 V_RHE). The results obtained can facilitate research on the design of other transition‐metal dichalcogenide electrocatalysts for the reduction of CO₂ to valuable fuels.     

Amorphous Bimetallic Oxide–Graphene Hybrids as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn–Air Batteries

Metal oxides of earth‐abundant elements are promising electrocatalysts to overcome the sluggish oxygen evolution and oxygen reduction reaction (OER/ORR) in many electrochemical energy‐conversion devices. However, it is difficult to control their catalytic activity precisely. Here, a general three‐stage synthesis strategy is described to produce a family of hybrid materials comprising amorphous bimetallic oxide nanoparticles anchored on N‐doped reduced graphene oxide with simultaneous control of nanoparticle elemental composition, size, and crystallinity. Amorphous Fe_0.5Co_0.5O_x is obtained from Prussian blue analog nanocrystals, showing excellent OER activity with a Tafel slope of 30.1 mV dec^?1 and an overpotential of 257 mV for 10 mA cm^?2 and superior ORR activity with a large limiting current density of ?5.25 mA cm^?2 at 0.6 V. A fabricated Zn–air battery delivers a specific capacity of 756 mA h g_Zn^?1 (corresponding to an energy density of 904 W h kg_Zn^?1), a peak power density of 86 mW cm^?2 and can be cycled over 120 h at 10 mA cm^?2. Other two amorphous bimetallic, Ni_0.4Fe_0.6O_x and Ni_0.33Co_0.67O_x , are also produced to demonstrate the general applicability of this method for synthesizing binary metal oxides with controllable structures as electrocatalysts for energy conversion.     

Enhanced CO Affinity on Cu Facilitates CO2 Electroreduction toward Multi-Carbon Products

Electrochemical CO₂ reduction reaction (CO₂RR) is a promising strategy for waste CO₂ utilization and intermittent electricity storage. Herein, it is reported that bimetallic Cu/Pd catalysts with enhanced *CO affinity show a promoted CO₂RR performance for multi-carbon (C2+) production under industry-relevant high current density. Especially, bimetallic Cu/Pd-1% catalyst shows an outstanding CO₂-to-C2+ conversion with 66.2% in Faradaic efficiency (FE) and 463.2 mA cm⁻² in partial current density. An increment in the FE ratios of C2+ products to CO  for Cu/Pd-1% catalyst further illuminates a preferable C2+ production. In situ Raman spectra reveal that the atop-bounded CO is dominated by low-frequency band CO on Cu/Pd-1% that leads to C2+ products on bimetallic catalysts, in contrast to the majority of high-frequency band CO on Cu that favors the formation of CO. Density function theory calculation confirms that bimetallic Cu/Pd catalyst enhances the *CO adsorption and reduces the Gibbs free energy of the C C coupling process, thereby favoring the formation of C2+ products.