Defect Engineering in Earth-Abundant Cu_(2)ZnSnSe_(4) Absorber Using Efficient Alkali Doping for Flexible and Tandem Solar Cell Applications

To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1%with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92%for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(~1.0 eV)so that the tandem cell yielded an efficiency of 20%.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.

Toward practical photoelectrochemical water splitting and CO_(2) reduction using earth-abundant materials

Photoelectrochemical(PEC)fuel generation from water splitting and CO_(2)reduction(CO_(2)R)utilizing solar energy holds immense potential to solve the current energy and environmental issues.In the past decades,numerous studies have been devoted to this fast-growing research field,and it is essential to develop efficient photoelectrodes with earth-abundant materials for the practical application of PEC systems.A thorough review of earth-abundant materials and associated devices for PEC fuel generation is beneficial to uncover the inherent obstacles and pave the way for future research.Herein,we summarize the recent progress of earth-abundant light-absorbers and cocatalysts in the PEC systems.The unbiased configurations and scaling-up strategies of PEC devices using earth-abundant materials are examined.A comparison between PEC water splitting and CO_(2)R is carried out to promote better understanding of the design principles for practical materials and devices.Last,the prospects on advanced materials,underlying mechanisms,and reaction systems of PEC water splitting and CO_(2)R are proposed.

Earth-abundant magnetite with carbon coatings as reversible cathodes for stretchable zinc-ion batteries

Earth-abundant magnetite(Fe_(3)O_(4))as cathode materials in aqueous zinc-ion batteries(ZIBs)is limited by its very low capacity and poor cycling.Here,a combined strategy based on carbon coating and electrolyte optimization is adopted to improve the performance of Fe_(3)O_(4).The Zn-Fe_(3)O_(4)@C batteries display specific capacities of 93 mAh g^(−1) and 81%capacity retention after 200 cycles.Such performance is attributed to the enhanced electrical conductivity and structural stability of Fe_(3)O_(4)@C nanocomposites with suppressed iron dissolution.Experimental analysis reveals that the charge storage is contributed by diffusion-limited redox reactions and surface-controlled pseudocapacitance.A stretchable Zn-Fe_(3)O_(4)@C battery is further fabricated,showing stable performance when it is bent or stretched.Fe_(3)O_(4) is a promising cathode material for cost-effective,safe,sustainable and wearable energy supplies.

Asymmetric Transfer and Pressure Hydrogenation with Earth-Abundant Transition Metal Catalysts

The asymmetric transfer and pressure hydrogenation of various unsaturated substrates provides a succinct pathway to important chiral intermediates and products such as chiral alcohols, amines, and alkanes. The use of earth-abundant transition metals such as Fe, Co, Ni, and Cu in hydro- genation reactions provides an attractive alternative to traditionally used metals such as Ru, Rh, Ir, and Pd because they are comparatively inexpensive, less toxic, and as their name suggests, more abundant in nature. Earth-abundant transition metal-catalyzed asymmetric hydrogenation is rapidly becoming an important area of research. This review summarizes advances in the asymmetric hydrogenation of unsaturated bonds （ketones, imines, and alkenes） with earth-abundant transition metals.

Recent Advances in Photocatalytic CO2 Reduction Using Earth-Abundant Metal Complexes-Derived Photocatalysts

Photochemical reduction of CO2 with H20 into energy-rich chemicals using inexhaustible solar energy is an appealing strategy to simultaneously address the global energy and environmental issues. Earth-abundant metal complexes show promising application in this field due to their easy availability, rich redox valence and tunable property. Great progress has been seen on catalytic reduction of CO2 under visible light illumination employing earth-abundant metal complexes and their hybrids as key contributors, especially for producing CO and HCOOH via the two-electron reduction process. In this minireview, we will summarize and update advances on earth-abundant metal complex-derived photocatalytic system for visible-light driven CO2 photoreduction over the last 5 years. Homogeneous earth-abundant metal complex photocatalysts and earth-abundant metal complex derived hybrid photocatalysts were both presented with focus on efficient improvement strategy.

Thermal-reductive transformations of carbon dioxide catalyzed by small molecules using earth-abundant elements

In the present review, we summarize the progress for thermal reductive transformations of CO2 catalyzed by small homogeneous catalysts using earth-abundant elements. Three main types of transformations categorized by the use of different reductants(hydrogen, hydrosilanes, and boranes), in which no C–C bond formation is involved, are surveyed.

Constructing low-cost Ni3C/twin-crystal Zn0.5Cd0.5S heterojunction/homojunction nanohybrids for efficient photocatalytic H2 evolution

The development of low-cost semiconductor photocatalysts for highly efficient and durable photocatalytic H2 evolution under visible light is very challenging.In this study,we combine low-cost metallic Ni3C cocatalysts with twin nanocrystal Zn0.5Cd0.5S(ZCS)solid solution homojunctions for an efficient visible-light-driven H2 production by a simple approach.As-synthesized Zn0.5Cd0.5S-1%Ni3C(ZCS-1)heterojunction/homojunction nanohybrid exhibited the highest photocatalytic H2-evolution rate of 783μmol h‒1 under visible light,which is 2.88 times higher than that of pristine twin nanocrystal ZCS solid solution.The apparent quantum efficiencies of ZCS and ZCS-1 are measured to be 6.13%and 19.25%at 420 nm,respectively.Specifically,the homojunctions between the zinc blende and wurtzite segments in twin nanocrystal ZCS solid solution can significantly improve the light absorption and separation of photogenerated electron-hole pairs.Furthermore,the heterojunction between ZCS and metallic Ni3C NP cocatalysts can efficiently trap excited electrons from ZCS solid solution and enhance the H2-evolution kinetics at the surface for improving catalytic activity.This study demonstrates a unique one-step strategy for constructing heterojunction/homojunction hybrid nanostructures for a more efficient photocatalytic H2 evolution compared to other noble metal photocatalytic systems.

Earth abundant spinel for hydrogen production in a chemical looping scheme at 550℃

Operating chemical looping process at mid-temperatures(550–750℃)presents exciting potential for the stable production of hydrogen.However,the reactivity of oxygen carriers is compromised by the detrimental effect of the relatively low temperatures on the redox kinetics.Although the reactivity at mid-temperature can be improved by the addition of noble metals,the high cost of these noble metal containing materials significantly hindered their scalable applications.In the current work,we propose to incorporate earth-abundant metals into the ironbased spinel for hydrogen production in a chemical looping scheme at mid-temperatures.Mn0.2Co0.4Fe2.4O4 shows a high hydrogen production performance at the average rate of~0.62 mmol g^(-1) min^(-1) and a hydrogen yield of~9.29 mmol g^(-1) with satisfactory stability over 20 cycles at 550℃.The mechanism studies manifest that the enhanced hydrogen production performance is a result of the improved oxygen-ion conductivity to enhance reduction reaction and high reactivity of reduced samples with steam.The performance of the oxygen carriers in this work is comparable to those noble-metal containing materials,enabling their potential for industrial applications.

Recent Advances in Mn,Fe,Co,and Ni-Catalyzed Organic Reactions

This paper reviewed the recent research progress of organic reactions catalyzed by four typical earthabundant and 3d metal catalysts:Mn,Fe,Co,and Ni complexes and mainly focused on the reactions in which these 3d metal catalysts exhibited obvious advantages over other catalysts.The mechanism that makes these 3d metal catalysts show unusual properties is another focus of this paper.An outlook on 3d metal complexes-catalyzed organic reactions was also considered.

Metal-organic framework based nanomaterials for electrocatalytic oxygen redox reaction

Due to the severe environmental issues, many advanced technologies, typically fuel cells and metal-air batteries have aroused widespread concerns and been intensively studied in recent years. However, oxygen redox reactions including oxygen evolution reaction(OER) and oxygen reduction reaction(ORR) as the core reactions suffer from sluggish kinetics of the multiple electron transfer process. Currently, Pt, RuO_2, and IrO_2 are considered to be the benchmark catalysts for ORR and OER, but their high price, scarcity and instability hinder them from large-scale application. To overcome these limits, exploring alternative electrocatalysts with low cost, high activity, long-term stability, and earth-abundance is of extreme urgency. Metal-organic frameworks(MOFs) are a family of inorganic-organic hybrid materials with high surface areas and tunable structures, making them proper as catalyst candidates. Herein, the recent progress of MOFs and MOF-derived materials for ORR and OER is systematically reviewed, and the relationship between compositions and electrochemical performance is discussed. It is expected that this review can be helpful for the future development of related MOF-based materials with excellent electrochemical performance.

Iron-Catalysed C(sp^(2))-H Borylation with Expanded Functional Group Tolerance

Arene C(sp^(2))-H bond borylation offers direct and efficient access to aryl boronic esters.Using in situ catalyst activation and photoirradiation,the iron-catalysed C(sp^(2))-H borylation reaction of carboarenes,pyrroles,and indoles has been developed using only bench-stable pre-catalysts and reagents.Good functional group tolerance was observed including those not reported using previous methods(ArNH_(2),ArOH,ArSiR_(3),ArP(O)(O)_(2),ArC(O)NR_(2)).Mechanistic studies revealed iron-catalysed reductive deoxygenation,C—F protodefluorination,and a demethylation of aryl methyl ethers by C—O sigma bond hydroboration.

Markovnikov-Selective Hydroboration of Aryl Alkenes Enabled by a Simple Nickel Salt

The sustainable development of synthetic reactions catalyzed by earth-abundant metals is one of the principal goals in homogeneous catalysis.However,so far most of the protocols are still plagued by sophisticated ligands,hazardous activators,high catalyst loading(1—10 mol%)and/or multistep synthesis of the metal complexes in the process development.Consequently,the development of earth-abundant metal catalysts with high activity from commercially available metal salts is highly desirable for practical utilization of base metal catalyzed synthetic methodology.Herein,we report the catalyst generated in situ from a mixture of catalytic amounts of Ni(acac)_(2)(as low as 0.005 mol%)and CsF,which is found highly active for Markovnikov-selective hydroboration of vinylarenes,including 1,1-disubstituted vinylarenes and internal olefins,affording a wide range of secondary and tertiary alkyl boronates in excellent yields.Mechanistic experiments indicate that the key to the success of this catalysis is the use of CsF,which in combination with pinacolborane acts as an effective activator for Ni(acac)_(2),probably generating metastable Ni nanoparticles in situ that demonstrate high activity in the catalytic hydroboration(TON up to 18800).

Scalable Amorphous NiFe(OH)x/Fe/Graphene Bifunctional Electrocatalyst via Solution-Corrosion for Water Splitting

The quest for net-zero emissions highlights the signifi-cance of hydrogen as a clean energy carrier,necessitating efficient production methods.Electrochemical water splitting emerges as a crucial method for hydrogen generation,with its further advancement hinging on the development of effective bifunctional catalysts that are efficient in both oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).In this study,we develop the bifunctional electrocatalyst NiFe(OH)x/Fe/graphene through a simple solution-corrosion approach.The overpotentials required for OER and HER to achieve a current density of 10 mA cm^(−2) are 237 and 42 mV,respectively,while the overall water splitting occurs at a low cell voltage of 1.51 V for the same current density.Remarkably,the catalyst displays robust stability exceeding 70 h at 20 mA cm^(−2) in 1 M KOH.When scaled to 10×10 cm^(2),its performance is comparable to that of a smaller size 0.5×0.5 cm^(2) electrode,indicating the scalability of our method and potential for industrial-scale hydrogen production.Trace incorporation of iron and the facilitation by graphene modify the electronic structures and coordination environment in the amorphous NiFe(OH)x/Fe/graphene composite.This alteration enhances the distribution of active sites and reduces kinetic barriers for both HER and OER,thereby increasing its bifunctional catalytic activity.This study not only introduces a novel catalyst design that incorporates in-situ Fe metal powder within OER-active catalysts to generate HER active sites for enabling bifunctionality,but also offers a pathway to manufacture high performance electrocatalysts for industrial applications.