Heterojunction Incorporating Perovskite and Microporous Metal–Organic Framework Nanocrystals for Efficient and Stable Solar Cells

In this paper,we present a facile approach to enhance the efficiency and stability of perovskite solar cells(PSCs)by incorporating perovskite with microporous indium-based metal–organic framework[In12O(OH)16(H2O)5(btc)6]n(In-BTC)nanocrystals and forming heterojunction light-harvesting layer.The interconnected micropores and terminal oxygen sites of In-BTC allow the preferential crystallization of perovskite inside the regular cavities,endowing the derived films with improved morphology/crystallinity and reduced grain boundaries/defects.Consequently,the In-BTC-modified PSC yields enhanced fill factor of 0.79 and power conversion efficiency(PCE)of 20.87%,surpassing the pristine device(0.76 and 19.52%,respectively).More importantly,over 80%of the original PCE is retained after 12 days of exposure to ambient environment(25°C and relative humidity of^65%)without encapsulation,while only about 35%is left to the pristine device.     

Highly Efficient Photoelectrocatalytic Reduction of CO2 to Methanol by a p–n Heterojunction CeO2/CuO/Cu Catalyst

Photoelectrocatalytic reduction of CO2 to fuels has great potential for reducing anthropogenic CO2 emissions and also lessening our dependence on fossil fuel energy.Herein,we report the successful development of a novel photoelectrocatalytic catalyst for the selective reduction of CO2 to methanol,comprising a copper catalyst modified with flower-like cerium oxide nanoparticles(CeO2 NPs)(a n-type semiconductor)and copper oxide nanoparticles(CuO NPs)(a p-type semiconductor).At an applied potential of−1.0 V(vs SCE)under visible light irradiation,the CeO2 NPs/CuO NPs/Cu catalyst yielded methanol at a rate of 3.44μmol cm^−2 h^−1,which was approximately five times higher than that of a CuO NPs/Cu catalyst(0.67μmol cm^−2 h^−1).The carrier concentration increased by^108 times when the flower-like CeO2 NPs were deposited on the CuO NPs/Cu catalyst,due to synergistic transfer of photoexcited electrons from the conduction band of CuO to that of CeO2,which enhanced both photocatalytic and photoelectrocatalytic CO2 reduction on the CeO2 NPs.The facile migration of photoexcited electrons and holes across the p–n heterojunction that formed between the CeO2 and CuO components was thus critical to excellent light-induced CO2 reduction properties of the CeO2 NPs/CuO NPs/Cu catalyst.Results encourage the wider application of composite semiconductor electrodes in carbon dioxide reduction.     

Plasmonic Metal Mediated Charge Transfer in Stacked Core–Shell Semiconductor Heterojunction for Significantly Enhanced CO2 Photoreduction

Construction of core–shell semiconductor heterojunctions and plasmonic metal/semiconductor heterostructures represents two promising routes to improved light harvesting and promoted charge separation, but their photocatalytic activities are respectively limited by sluggish consumption of charge carriers confined in the cores, and contradictory migration directions of plasmon-induced hot electrons and semiconductor-generated electrons. Herein, a semiconductor/metal/semiconductor stacked core–shell design is demonstrated to overcome these limitations and significantly boost the photoactivity in CO₂ reduction. In this smart design, sandwiched Au serves as a “stone”, which “kills two birds” by inducing localized surface plasmon resonance for hot electron generation and mediating unidirectional transmission of conduction band electrons and hot electrons from TiO₂ core to MoS₂ shell. Meanwhile, upward band bending of TiO₂ drives core-to-shell migration of holes through TiO₂–MoS₂ interface. The co-existence of TiO₂ → Au → MoS₂ electron flow and TiO₂ → MoS₂ hole flow contributes to spatial charge separation on different locations of MoS₂ outer layer for overall redox reactions. Additionally, reduction potential of photoelectrons participating in the CO₂ reduction is elaborately adjusted by tuning the thickness of MoS₂ shell, and thus the product selectivity is delicately regulated. This work provides fresh hints for rationally controlling the charge transfer pathways toward high-efficiency CO₂ photoreduction.     

In Situ 1D Carbon Chain-Mail Catalyst Assembly for Stable Lithium–Sulfur Full Batteries

The main obstacles for the commercial application of Lithium–Sulfur (Li–S) full batteries are the large volume change during charging/discharging process, the shuttle effect of lithium polysulfide (LiPS), sluggish redox kinetics, and the indisciplinable dendritic Li growth. Especially the overused of metal Li leads to the low utilization of active Li, which seriously drags down the actual energy density of Li–S batteries. Herein, an efficient design of dual-functional CoSe electrocatalyst encapsulated in carbon chain-mail (CoSe@CCM) is employed as the host both for the cathode and anode regulation simultaneously. The carbon chain-mail constituted by carbon encapsulated layer cross-linking with carbon nanofibers protects CoSe from the corrosion of chemical reaction environment, ensuring the high activity of CoSe during the long-term cycles. The Li–S full battery using this carbon chain-mail catalyst with a lower negative/positive electrode capacity ratio (N/P < 2) displays a high areal capacity of 9.68 mAh cm⁻² over 150 cycles at a higher sulfur loading of 10.67 mg cm⁻². Additionally, a pouch cell is stable for 80 cycles at a sulfur loading of 77.6 mg, showing the practicality feasibility of this design.     

Defect Engineering on Carbon‑Based Catalysts for Electrocatalytic CO2 Reduction

Electrocatalytic carbon dioxide(CO2)reduction(ECR)has become one of the main methods to close the broken carbon cycle and temporarily store renewable energy,but there are still some problems such as poor stability,low activity,and selectivity.While the most promising strategy to improve ECR activity is to develop electrocatalysts with low cost,high activity,and long-term stability.Recently,defective carbon-based nanomaterials have attracted extensive attention due to the unbalanced electron distribution and electronic structural distortion caused by the defects on the carbon materials.Here,the present review mainly summarizes the latest research progress of the construction of the diverse types of defects(intrinsic carbon defects,heteroatom doping defects,metal atomic sites,and edges detects)for carbon materials in ECR,and unveil the structure-activity relationship and its catalytic mechanism.The current challenges and opportunities faced by high-performance carbon materials in ECR are discussed,as well as possible future solutions.It can be believed that this review can provide some inspiration for the future of development of high-performance ECR catalysts.     

A Tumor-Microenvironment-Responsive Lanthanide–Cyanine FRET Sensor for NIR-II Luminescence-Lifetime In Situ Imaging of Hepatocellular Carcinoma

Deep tissue imaging in the second near-infrared (NIR-II) window holds great promise for widespread fundamental research. However, inhomogeneous signal attenuation due to tissue absorption and scattering hampers its application for accurate in vivo biosensing. Here, lifetime-based in situ hepatocellular carcinoma (HCC) detection in NIR-II region is presented using a tumor-microenvironment (peroxynitrite, ONOO⁻)-responsive lanthanide–cyanine Förster resonance energy transfer (FRET) nanosensor. A specially designed ONOO⁻-responsive NIR-II dye, MY-1057, is synthesized as the FRET acceptor. Robust lifetime sensing is demonstrated to be independent of tissue penetration depth. Tumor lesions are accurately distinguished from normal tissue due to the recovery lifetime. Magnetic resonance imaging and liver dissection results illustrate the reliability of lifetime-based detection in single and multiple HCC models. Moreover, the ONOO⁻ amount can be calculated according to the standard curve.     

Secondary Anti-Solvent Treatment for Efficient 2D Dion–Jacobson Perovskite Solar Cells

Surface defects-mediated nonradiative recombination plays a critical role in the performance and stability of perovskite solar cells (PSCs) and surface post-treatment is widely used for efficient PSCs. However, the commonly used surface passivation strategies are one-off and the passivation defect ability is limited, which can only solve part of the defects in the topmost surface area. Here, a secondary anti-solvent strategy is proposed to further reduce surface defects based on conventional surface passivation for the first time. Based on this, the crystallization quality of 2D Dion–Jacobson perovskite is enhanced and the surface defects density is further reduced by nearly two orders. In addition, a gradient structure of perovskite with n = 2 phases located at the top of the film and 3D-like phases located at the bottom of the film can also be obtained. The modulated perovskite film boosts the efficiency of 2D perovskites (n = 5) up to 19.55%. This strategy is also very useful in other anti-solvent processed perovskite dipping systems, which paves a promising avenue for minimizing surface defects toward highly efficient perovskite devices.     

Less-Coordinated Atomic Copper-Dimer Boosted Carbon–Carbon Coupling During Electrochemical CO2 Reduction

This work reports a metal–organic framework (MOF) with less-coordinated copper dimers, which displays excellent electrochemical CO₂ reduction (eCO₂RR) performance with an advantageous current density of 0.9 A cm⁻² and a high Faradaic efficiency of 71% to C₂ products. In comparison with MOF with Cu monomers that are present as Cu₁ O₄ with a coordination number of 3.8 ± 0.2, Cu dimers exist as O₃Cu₁···Cu₂O₂ with a coordination number of 2.8 ± 0.1. In situ characterizations together with theoretical calculations reveal that two *CO intermediates are stably adsorbed on each site of less-coordinated Cu dimers, which favors later dimerization via a key intermediate of *CH₂CHO. The highly unsaturated dual-atomic Cu provides large-quantity and high-quality actives sites for carbon–carbon coupling, achieving the optimal trade-off between activity and selectivity of eCO₂RR to C₂ products.     

3D Seed?Germination?Like MXene with In Situ Growing CNTs/Ni Heterojunction for Enhanced Microwave Absorption via Polarization and Magnetization

Ti3C2Tx MXene is widely regarded as a potential microwave absorber due to its dielectric multi-layered structure. However, missing magnetic loss capability of p...     

Porous Host–Guest MOF-Semiconductor Hybrid with Multisites Heterojunctions and Modulable Electronic Band for Selective Photocatalytic CO2 Conversion and H2 Evolution

Optimizing catalysts for competitive photocatalytic reactions demand individually tailored band structure as well as intertwined interactions of light absorption, reaction activity, mass, and charge transport.  Here, a nanoparticulate host–guest structure is rationally designed that can exclusively fulfil and ideally control the aforestated uncompromising requisites for catalytic reactions. The all-inclusive model catalyst consists of porous Co₃O₄ host and Zn_xCd_1-xS guest with controllable physicochemical properties enabled by self-assembled hybrid structure and continuously amenable band gap. The effective porous topology nanoassembly, both at the exterior and the interior pores of a porous metal–organic framework (MOF), maximizes spatially immobilized semiconductor nanoparticles toward high utilization of particulate heterojunctions for vital charge and reactant transfer. In conjunction, the zinc constituent band engineering is found to regulate the light/molecules absorption, band structure, and specific reaction intermediates energy to attain high photocatalytic CO₂ reduction selectivity. The optimal catalyst exhibits a H₂-generation rate up to 6720 µmol g⁻¹ h⁻¹ and a CO production rate of 19.3 µmol g⁻¹ h⁻¹. These findings provide insight into the design of discrete host–guest MOF-semiconductor hybrid system with readily modulated band structures and well-constructed heterojunctions for selective solar-to-chemical conversion.     

Promoting Electrocatalytic CO2 Reduction to CH4 by Copper Porphyrin with Donor–Acceptor Structures

Molecular catalysts have been receiving increasingly attention in the electrochemical CO₂ reduction reaction (CO₂RR) with attractive features such as precise catalytic sites and tunable ligands. However, the insufficient activity and low selectivity of deep reduction products restrain the utilization of molecular catalysts in CO₂RR. Herein, a donor–acceptor modified Cu porphyrin (CuTAPP) is developed, in which amino groups are linked to donate electrons toward the central CuN₄ site to enhance the CO₂RR activity. The CuTAPP catalyst exhibited an excellent CO₂-to-CH₄ electroreduction performance, including a high CH₄ partial current density of 290.5 mA cm⁻² and a corresponding Faradaic efficiency of 54.8% at –1.63 V versus reversible hydrogen electrode in flow cells. Density functional theory calculations indicated that CuTAPP presented a much lower energy gap in the pathway of producing *CHO than Cu porphyrin without amino group modification. This work suggests a useful strategy of introducing designed donor–acceptor structures into molecular catalysts for enhancing electrochemical CO₂ conversion toward deep reduction products.     

Photocatalytic decomposition of VOCs by AC–TiO2 and EG–TiO2 nanocomposites

Clean Technologies and Environmental Policy - In this study, TiO2 nanoparticles (NPs)-based catalysts were prepared for the photocatalytic removal of toluene as a model VOC from air under UV light....     

In Situ Investigation of Reversible Exsolution/Dissolution of CoFe Alloy Nanoparticles in a Co-Doped Sr2Fe1.5Mo0.5O6−δ Cathode for CO2 Electrolysis

Reversible exsolution and dissolution of metal nanoparticles in perovskite has been investigated as an efficient strategy to improve CO₂ electrolysis performance. However, fundamental understanding with regard to the reversible exsolution and dissolution of metal nanoparticles in perovskite is still scarce. Herein, in situ exsolution and dissolution of CoFe alloy nanoparticles in Co-doped Sr₂Fe_1.5Mo_0.5O_6–δ (SFMC) revealed by in situ X-ray diffraction, scanning transmission electron microscopy, environmental scanning electron microscopy, and density functional theory calculations are reported. Under a reducing atmosphere, facile exsolution of Co promotes reduction of the Fe cation to generate CoFe alloy nanoparticles in SFMC, accompanied by structure transformation from double perovskite to layered perovskite at 800 °C. Under an oxidizing atmosphere, spherical CoFe alloy nanoparticles are first oxidized to flat CoFeO_x nanosheets, and then dissolved into the bulk with structure evolution from layered perovskite back to double perovskite. Electrochemically, CO₂ electrolysis performance can be retrieved during 12 redox cycles due to the regenerative ability of the CoFe alloy nanoparticles. The anchoring of the CoFe alloy nanoparticles in SFMC perovskite via reduction shows enhanced CO₂ electrolysis performance and stability compared with the parent SFMC perovskite.     

Coupling a Sponge Metal Fibers Skeleton with In Situ Surface Engineering to Achieve Advanced Electrodes for Flexible Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) are regarded as promising next-generation energy storage systems, however, the uncontrollable dendrite formation and serious polysulfide shuttling severely hinder their commercial success. Herein, a powerful 3D sponge nickel (SN) skeleton plus in situ surface engineering strategy, to address these issues synergistically, is reported, and a high-performance flexible LSB device is constructed. Specifically, the rationally designed spray-quenched lithium metal on the SN matrix (solid electrolyte interface (SEI)@Li/SN), as dendrite inhibitor, combines the merits of the 3D lithiophilic SN skeleton and the in situ formed SEI layer derived from the spray-quenching process, and thereby exhibits a steady overpotential within 75 mV for 1500 h at 5 mA cm⁻²/10 mA h cm⁻². Meanwhile, in situ surface sulfurization of the SN skeleton hybridizing with the carbon/sulfur composite (SC@Ni₃S₂/SN) serves as efficient lithium polysulfide adsorbent to catalyze the overall reaction kinetics. COMSOL Multiphysics simulations and density functional theory calculations are further conducted to explore the underlying mechanisms. As a proof of concept, the well-designed SEI@Li/SN||SC@Ni₃S₂/SN full cell shows excellent electrochemical performance with a negative/positive ratio in capacity of ≈2 and capacity retention of 99.82% at 1 C under mechanical deformation. The novel design principles of these materials and electrodes successfully shed new light on the development of flexible LSBs.     

Facile In Situ Fabrication of Nanostructured Graphene–CuO Hybrid with Hydrogen Sulfide Removal Capacity

Nano-Micro Letters - A simple and scalable synthetic approach for one-step synthesis of graphene–CuO (TRGC) nanocomposite by an in situ thermo-annealing method has been developed. Using...     

Pyrazine-Functionalized Donor–Acceptor Covalent Organic Frameworks for Enhanced Photocatalytic H2 Evolution with High Proton Transport

The well-defined 2D or 3D structure of covalent organic frameworks (COFs) makes it have great potential in photoelectric conversion and ions conduction fields. Herein, a new donor–accepter (D–A) COF material, named PyPz-COF, constructed from electron donor 4,4′,4″,4′″-(pyrene-1,3,6,8-tetrayl)tetraaniline and electron accepter 4,4′-(pyrazine-2,5-diyl)dibenzaldehyde with an ordered and stable π-conjugated structure is reported. Interestingly, the introduction of pyrazine ring endows the PyPz-COF a distinct optical, electrochemical, charge-transfer properties, and also brings plentiful CN groups that enrich the proton by hydrogen bonds to enhance the photocatalysis performance. Thus, PyPz-COF exhibits a significantly improved photocatalytic hydrogen generation performance up to 7542 µmol g⁻¹ h⁻¹ with Pt as cocatalyst, also in clear contrast to that of PyTp-COF without pyrazine introduction (1714 µmol g⁻¹ h⁻¹). Moreover, the abundant nitrogen sites of the pyrazine ring and the well-defined 1D nanochannels enable the as-prepared COFs to immobilize H₃PO₄ proton carriers in COFs through hydrogen bond confinement. The resulting material has an impressive proton conduction up to 8.10 × 10⁻² S cm⁻¹ at 353 K, 98% RH. This work will inspire the design and synthesis of COF-based materials with both efficient photocatalysis and proton conduction performance in the future.