Electrocatalytic Synthesis of Urea: An In-depth Investigation from Material Modification to Mechanism Analysis.

Industrial urea synthesis production uses NH3 from the Haber-Bosch method, followed by the reaction of NH3 with CO2, which is an energy-consuming technique. More thorough evaluations of the electrocatalytic C-N coupling reaction are needed for the urea synthesis development process, catalyst design, and the underlying reaction mechanisms. However, challenges of adsorption and activation of reactant and suppression of side reactions still hinder its development, making the systematic review necessary. This review meticulously outlines the progress in electrochemical urea synthesis by utilizing different nitrogen (NO3 -, N2, NO2 -, and N2O) and carbon (CO2 and CO) sources. Additionally, it delves into advanced methods in materials design, such as doping, facet engineering, alloying, and vacancy introduction. Furthermore, the existing classes of urea synthesis catalysts are clearly defined, which include 2D nanomaterials, materials with Mott-Schottky structure, materials with artificially frustrated Lewis pairs, single-atom catalysts (SACs), and heteronuclear dual-atom catalysts (HDACs). A comprehensive analysis of the benefits, drawbacks, and latest developments in modern urea detection techniques is discussed. It is aspired that this review will serve as a valuable reference for subsequent designs of highly efficient electrocatalysts and the development of strategies to enhance the performance of electrochemical urea synthesis.

A sheet-like tin-based metal-organic framework with enhanced lithium storage.

A novel sheet-like tin-based metal-organic framework exhibited a specific capacity for lithium storage as high as 1033.3 mAh g-1 at 200 mA g-1 with excellent cycling stability. This framework, due to its unique porous structure and multiple lithium storage sites, could better cope with challenges occurring during lithium insertion/extraction than could traditional tin materials.

Fundamentals and Recent Progress in Magnetic Field Assisted CO2 Capture and Conversion.

CO2 capture and conversion technology are highly promising technologies that definitely play a part in the journey towards carbon neutrality. Releasing CO2 by mild stimulation and the development of high efficiency catalytic processes are urgently needed. The magnetic field, as a thermodynamic parameter independent of temperature and pressure, is vital in the enhancement of CO2 capture and conversion process. In this review, the recent progress of magnetic field-enhanced CO2 capture and conversion is comprehensively summarized. The theoretical fundamentals of magnetic field on CO2 adsorption, release and catalytic reduction process are discussed, including the magnetothermal, magnetohydrodynamic, spin selection, Lorentz forces, magnetoresistance and spin relaxation effects. Additionally, a thorough review of the current progress of the enhancement strategies of magnetic field coupled with a variety of fields (including thermal, electricity, and light) is summarized in the aspect of CO2 related process. Finally, the challenges and prospects associated with the utilization of magnetic field-assisted techniques in the construction of CO2 capture and conversion systems are proposed. This review offers a reference value for the future design of catalysts, mechanistic investigations, and practical implementation for magnetic field enhanced CO2 capture and conversion.

Versatile nicotinamide enabling dendrite-free and efficient deposition for aqueous Zn-I2 batteries.

This study introduces a versatile electrolyte additive, nicotinamide, for zinc anodes, aiming to facilitate uniform deposition and suppress water-induced side reactions. The molecular structure, consisting of a pyridine ring and an amide function group, endows NTA molecules with the ability to regulate electrolyte pH, enhance nucleation overpotential, and constrain 2D diffusion of Zn2+. As a result, the full battery configuration with this additive achieved an impressive lifespan of over 10 000 cycles.

Prelithiated rigid polymer with high ionic conductivity as silicon-based anode binder for lithium-ion battery.

Silicon-based electrodes suffer from rapid performance degradation derived from a severe volume expansion during cycling in lithium-ion batteries, and using elaborately designed polymer binders is deemed an efficient tactic to tackle the above thorny issues. In this study, a water-soluble rigid-rod poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) polymer is described and employed as the binder for Si-based electrodes for the first time. The nematic rigid PBDT bundles wrapped around the Si nanoparticles by hydrogen bonding effectively inhibit the volume expansion of the Si and promote the formation of stable solid electrolyte interfaces (SEI). Moreover, the prelithiated PBDT binder with high ionic conductivity (3.2 × 10-4 S cm-1) not only improves the Li-ions transportation behaviors in the electrode but can also partially compensate for the irreversible Li source consumption during SEI formation. Consequently, the cycling stability and initial coulombic efficiency of the Si-based electrodes with the PBDT binder are remarkably enhanced compared to that with the PVDF binder. This work demonstrates the molecular structure and prelithiation strategy of the polymer binder that play a crucial role in improving the performance of Si-based electrodes with high-volume expansion.

Ultralow-Temperature SnO2 Electron Transport Layers Fabricated by Intermediate-Controlled Chemical Bath Deposition for Highly Efficient Perovskite Solar Cells.

As electron transport layers (ETLs) in perovskite solar cells (PSCs), tin oxide (SnO2 ) possess high carrier mobilities with appropriate energy band alignment and high optical transmittance. Herein, SnO2 ETLs were fabricated by intermediate-controlled chemical bath deposition (IC-CBD) at ultralow temperature, where the chelating agent effectively altered the nucleation and growth process. Compared with conventional CBD, SnO2 ETLs fabricated by IC-CBD had lower defects, smooth surface, good crystallinity, and remarkable interfacial contact with perovskite, resulting in good quality of perovskite, high photovoltaic performance (23.17 %), and enhanced stability of devices.

14.31 % Power Conversion Efficiency of Sn-Based Perovskite Solar Cells via Efficient Reduction of Sn4.

The photoelectric properties of nontoxic Sn-based perovskite make it a promising alternative to toxic Pb-based perovskite. It has superior photovoltaic performance in comparison to other Pb-free counterparts. The facile oxidation of Sn2+ to Sn4+ presents a notable obstacle in the advancement of perovskite solar cells that utilize Sn, as it adversely affects their stability and performance. The study revealed the presence of a Sn4+ concentration on both the upper and lower surfaces of the perovskite layer. This discovery led to the adoption of a bi-interface optimization approach. A thin layer of Sn metal was inserted at the two surfaces of the perovskite layer. The implementation of this intervention yielded a significant decrease in the levels of Sn4+ and trap densities. The power conversion efficiency of the device was achieved at 14.31 % through the optimization of carrier transportation. The device exhibited operational and long-term stability.

Photothermal CO-PROX reaction over ternary CuCoMnOx spinel oxide catalysts: the effect of the copper dopant and thermal treatment.

The purification of carbon monoxide in H2-rich streams is an urgent problem for the practical application of fuel cells, and requires the development of efficient and economical catalysts for the preferential oxidation of CO (CO-PROX). In the present work, a facile solid phase synthesis method followed by an impregnation method were adopted to prepare a ternary CuCoMnOx spinel oxide, which shows superior catalytic performance with CO conversion of 90% for photothermal CO-PROX at 250 mW cm-2. The dopant of copper species leads to the incorporation of Cu ions into the CoMnOx spinel lattice forming a ternary CuCoMnOx spinel oxide. The appropriate calcination temperature (300 °C) contributes to the generation of abundant oxygen vacancies and strong synergetic Cu-Co-Mn interactions, which are conducive to the mobility of oxygen species to participate in CO oxidation reactions. On the other hand, the highest photocurrent response of CuCoMnOx-300 also promotes the photo-oxidation activity of CO due to the high carrier concentration and efficient carrier separation. In addition, the in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed that doping copper species could enhance the CO adsorption capacity of the catalyst due to the generation of Cu+ species, which significantly increased the CO oxidation activity of the CuCoMnOx spinel oxide. The present work provides a promising and eco-friendly solution to remove the trace CO in H2-rich gas over CuCoMnOx ternary spinel oxide with solar light as the only energy source.

Crab Shell-Derived SnS2/C and FeS2/C Carbon Composites as Anodes for High-Performance Sodium-Ion Batteries.

The demand for energy storage devices has increased significantly, and the sustainable development of lithium-ion batteries is limited by scarce lithium resources. Therefore, alternative sodium-ion batteries which are rich in resource may become more competitive in the future market. In this work, we synthesized low-cost SnS2/C and FeS2/C anode materials of sodium-ion batteries which used waste crab shells as biomass carbon precursor. The SnS2 nanosheet and FeS2 nanosphere structures are deposited on the crab shell-derived carbon through simple hydrothermal reaction. Due to the coexistence of transition metal dichalcogenides (TMDs) and crab-derived biomass carbon, the anode material has excellent cycle stability and rate performance. SnS2/C and FeS2/C deliver capacities of 535.4 and 479 mA h g-1 at the current density of 0.1 A g-1, respectively. This study explored an effective and economical strategy to use biomass and TMDs to construct high-performance sodium-ion batteries.

Systematic investigation of metal dopants and mechanism for the SnO2 electron transport layer in perovskite solar cells.

SnO2, the most promising alternative to TiO2 as the electron transport layer (ETL), has attracted great attention for perovskite solar cells (PSCs) due to its high bulk electron mobility, good band energy at the ETL/perovskite interface, and high chemical stability. To enable more efficient carrier transfer and extraction, elemental doping with different metal cations has been studied in SnO2 ETLs. However, the systematic investigation of the doping mechanism lag far behind their efficiency promotion. In this paper, elements of the same main group (Li, Na, K) and period (K, Ca, Ga) have been selected for doping in SnO2. The results showed that among the properties of the dopants, the electronegativity has the greatest influence. The smaller the electronegativity of the doping species, the more conducive it is to carrier transmission and separation. The corresponding mechanism was proposed and discussed. At last, an efficiency of 20.92% of PSCs based on SnO2-K was achieved. In addition, the doped SnO2 is more beneficial for the growth of perovskite crystals, thus reducing grain boundaries and enhancing the stability of the device.

Enhancing Lithium-Sulfur Battery Performance by MXene, Graphene, and Ionic Liquids: A DFT Investigation.

The efficacy of lithium-sulfur (Li-S) batteries crucially hinges on the sulfur immobilization process, representing a pivotal avenue for bolstering their operational efficiency and durability. This dissertation primarily tackles the formidable challenge posed by the high solubility of polysulfides in electrolyte solutions. Quantum chemical computations were leveraged to scrutinize the interactions of MXene materials, graphene (Gr) oxide, and ionic liquids with polysulfides, yielding pivotal binding energy metrics. Comparative assessments were conducted with the objective of pinpointing MXene materials, with a specific focus on d-Ti3C2 materials, evincing augmented binding energies with polysulfides and ionic liquids demonstrating diminished binding energies. Moreover, a diverse array of Gr oxide materials was evaluated for their adsorption capabilities. Scrutiny of the computational outcomes unveiled an augmentation in the solubility of selectively screened d-Ti3C2 MXene and ionic liquids-vis à vis one or more of the five polysulfides. Therefore, the analysis encompasses an in-depth comparative assessment of the stability of polysulfide adsorption by d-Ti3C2 MXene materials, Gr oxide materials, and ionic liquids across diverse ranges.

A Heat-Liquefiable Solid Precursor for Ambient Growth of Perovskites with High Tunability, Performance and Stability.

Halide perovskites are intensively studied for applications in optoelectronic devices because of their outstanding properties and relatively low cost. However, the common precursor solutions for perovskite fabrication are rather unstable in the presence of moisture and oxygen, limiting the large-scale low-cost production of perovskite. Herein, water is used counterintuitively to formulate an ambient stable perovskite precursor, which is peculiar in that it is solid at room temperature but becomes a liquid at 75 °C. The non-fluidity of the precursor stemmed from the water-assisted intermediate fiber assembly, conferring high damp air stability. Yet the heat-liquefiability made the precursor highly processible for perovskite growth, and when guided by polyvinyl pyrrolidone coordination with Pb2+ , the perovskite can preferentially grow along the [200] direction, significantly improving the film quality. To demonstrate the utility of the precursor, it has been used to fabricate self-driven halide perovskite photodetectors, which exhibited a low noise current of 2.0 × 10-14  A Hz-1/2 , a high specific detectivity up to 1.4 × 1013 Jones, and high stability of 20 days of operation with only < 5% external quantum efficiency decay. This type of solid-liquid convertible precursor opens up new opportunities for wider applications of perovskites.

Cascaded band gap design for highly efficient electron transport layer-free perovskite solar cells.

The elimination of the electron transport layer (ETL) to fabricate ETL-free perovskite solar cells (PSCs) could save manufacturing cost and time. However, the direct contact of the perovskite and transparent conducting oxide (TCO) electrodes results in mismatched energy level alignment and current leakage. Therefore, ETL-free PSCs suffer from unsatisfactory photovoltaic performance. Herein, a special perovskite material with a cascaded band gap, called gradient homojunction perovskite (GHJP), is designed and synthesized by a large cation-assisted method. The inherent nature of GHJP was the type-II cascaded energy level alignment, which could block holes during the electron collection. This facilitated the dissociation of the excitons in the GHJP. Due to the excellent properties, ETL-free PSCs based on GHJP obtained 20.55% PCE, which was over 90% higher than that of ETL-free PSCs based on the control perovskite material.

Unveiling the Effect of Solvents on Crystallization and Morphology of 2D Perovskite in Solvent-Assisted Method.

Controlling the crystallographic orientations of 2D perovskite is regarded as an effective way to improve the efficiency of PSCs based on 2D perovskite. In this paper, five different assistant solvents were selected to unveil the effect of solvents on crystallization and morphology of 2D perovskite in a solvent-assisted method. Results demonstrated that the effect of Lewis basicity on the crystallization process was the most important factor for preparing 2D perovskite. The stability of the intermediate, reacted between the solvent and the Pb2+, determined the quality of 2D film. The stronger the Lewis basicity was, the more obvious the accurate control effect on the top-down crystallization process of 2D perovskite would be. This could enhance the crystallographic orientation of 2D perovskite. The effect of Lewis basicity played a more important role than other properties of the solvent, such as boiling point and polarity.

Sulfur contributes to stable and efficient carbon-based perovskite solar cells.

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) is already higher than those of other thin-film photovoltaic technologies, but the stability issue limits their applications. The introduction of sulfur-based compounds in PSCs could contribute to their stability. Herein, sulfur-based compounds have been embedded into each functional layer to stabilize carbon-based PSCs (C-PSCs). Results showed that the simultaneous introduction of sulfur-based compounds could decrease the trap states of perovskite film, enlarge the grain size of perovskite, and accelerate the charge transfer and extraction, leading to an improved performance. Comparing with the device without sulfide (10.77%), all sulfide C-PSCs obtained a PCE of 15.38%. The stability test showed much better resistance to humidity and thermal stress for all sulfide C-PSCs. They could retain 80% of initial PCE after aging about 700 h at relative humidity (RH) 45% ± 10% and 80 °C.

Double shelled hollow CoS2@MoS2@NiS2 polyhedron as advanced trifunctional electrocatalyst for zinc-air battery and self-powered overall water splitting.

Electrocatalysts play important role in various energy conversion and storage devices. The catalytic performance of electrocatalysts can be enhanced through the increasement of intrinsic catalytic activity by optimizing electronic structure and the improvement of exposed active sites by designing proper nanostructures. In this work, CoS2@MoS2@NiS2 nano polyhedron with double-shelled structure was prepared using metal organic framework as a precursor. Due to the rational integration of multifunctional active center, the strong electronic interaction of the various component, the high electrochemical surface area and shortened mass transport induced by the special structure, CoS2@MoS2@NiS2 exhibits high catalytic activity for hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Specifically, low overpotentials of 156 and 200 mV was achieved to deliver a current density of 10 mA cm-2 for HER and OER, and a high half-wave potential of 0.80 V was observed for ORR. More importantly, the Zn-air battery assembled by CoS2@MoS2@NiS2 exhibits a high-power density of 80.28 mW cm-2 and could effectively drive overall water splitting. This work provides a new platform for designing multifunctional catalysts with high activity for energy conversion and storage.

A double perovskite participation for promoting stability and performance of Carbon-Based CsPbI2Br perovskite solar cells.

All-inorganic perovskite materials (Typically: CsPbI2Br) have attracted enormous attention due to their illustrious thermal stability and appropriate bandgap, and their use in perovskite solar cells (PSCs) has been extensively investigated. However, the inevitable defects of the perovskite layer, energy level mismatch between perovskite and carbon electrodes, and the phase instability of CsPbI2Br limit the power conversion efficiency (PCE) and stability of carbon-based CsPbI2Br PSCs. Herein, we demonstrate a simple and effective strategy for regulating energy level, inhibiting carrier recombination, and delaying the degradation of perovskite by modifying the surface of CsPbI2Br with a new type of 2D perovskite Cs2PtI6. The carbon-based CsPbI2Br PSCs achieve a higher PCE (13.69 %) than the control device (11.10 %). The excellent matching of the energy level and suppression of charge carrier recombination should be responsible for the improvement in efficiency. Furthermore, the excellent hydrophobic performance of Cs2PtI6 enhances the moisture resistance of the device. This study provides a potential strategy for improving the performance and stability of all-inorganic CsPbI2Br PSCs.

Recent progress in metal sulfide-based electron transport layers in perovskite solar cells.

High-quality electron transport layers (ETLs) are essential for stable and efficient perovskite solar cells (PSCs). Metal sulfides (MSs) are considered potential candidates for ETLs due to their high carrier mobility, low cost, and favorable chemical and physical stability. The quality of the MS films plays important role in the photovoltaic performance of PSCs. However, few reports focus on the relative preparation, characteristics, and corresponding mechanisms of MS-based ETLs. In this review, MS-based ETLs are summarized according to their preparation strategies and the mechanism. We hope that this review can help others understand the intrinsic phenomena of MS-based ETLs and motivate further investigations.

Solvent-assisted crystallization of two-dimensional Ruddlesden-Popper perovskite.

Two dimensional (2D) perovskite materials, are more stable than 3D perovskite materials, which could solve the stability issue of perovskite solar cells (PSCs). However, the photovoltaic conversion efficiency (PCE) of PSCs based on 2D perovskite materials was low, due to the high dielectric and quantum confinement of 2D perovskite. In this work, we propose a solvent-assisted method to prepare 2D perovskite films, where the solvent was distributed in a gradient. Therefore, the top-down crystallization process of 2D perovskite can be accurately controlled. The PCE of PSCs fabricated by the solvent-assisted method was enhanced by 48%, compared with the control device. For the packaged devices, the stability test demonstrated that 94% of the initial PCE was still maintained after 1500 hours of storage (25 °C, RH 40%). After carefully analyzing the photophysical process of the carriers in the PSCs based on 2D perovskite, the enhanced carrier transfer mechanism of the solvent-assisted method has been proposed.

Bimetallic Sulfide SnS2/FeS2 Nanosheets as High-Performance Anode Materials for Sodium-Ion Batteries.

Transition-metal sulfide SnS2 has aroused wide concern due to its high capacity and nanosheet structure, making it an attractive choice as the anode material in sodium-ion batteries. However, the large volume expansion and poor conductivity of SnS2 lead to inferior cycle stability as well as rate performance. In this work, FeS2 was in situ introduced to synchronously grow with SnS2 on rGO to prepare a heterojunction bimetallic sulfide nanosheet SnS2/FeS2/rGO composite. The composition and distinctive structure facilitate the rapid diffusion of Na+ and improve the charge transfer at the heterogeneous interface, providing sufficient space for volume expansion and improving anode materials' structural stability. SnS2/FeS2/rGO bimetallic sulfide electrode boasts a capacity of 768.3 mA h g-1 at the current density of 0.1 A g-1, and 541.2 mA h g-1 at the current density of 1 A g-1 in sodium-ion batteries, which is superior to that of either single metal sulfide SnS2 or FeS2. TDOS calculation further confirms that the binding of FeS2/SnS2-Na is more stable than FeS2 and SnS2 alone. The superior electrochemical performance of the SnS2/FeS2/rGO composite material makes it a promising candidate for sodium storage.