In thin-film photovoltaics, such as organic and perovskite solar cells, charge extraction selectivity is crucial. In order to improve selectivity, charge transporting layers (doped and undoped) are frequently used; however, it is not well understood how a charge transporting layer should be designed in order to ensure efficient extraction of majority carriers while blocking minority carriers. This study clarifies how well charge transporting layers with varying majority carrier conductivities block minority carriers. The charge extraction by a linearly increasing voltage technique is used to determine the surface recombination velocity of minority carriers in model system devices with varying majority carrier conductivity in the transporting layer. The results show that transporting layers with high conductivity for majority carriers do not block minority carriers—at least not at operating voltages close to or above the built-in voltage, due to direct bimolecular recombination across the transporting layer–absorber layer interface. Design principles are furthermore discussed and proposed to achieve selective charge extraction in thin-film solar cells using charge transporting layers.

Taking advantage of carbonaceous composite materials in electrocatalysis or photocatalysis is a promising pathway for transforming biomass resources into sustainable energy-conversion systems. Herein, a carbonaceous composite catalyst based on the monodispersed silver vanadate nanoparticles (Ag3VO4 NPs) modification of biomass-derived porous carbon (named as AVO/PC) is proposed for ultrasensitive and electrochemical rapid detection of p-nitrophenol (p-NP) under acidic condition. The radish-derived three-dimensional porous carbonaceous aerogels as supporter subtly introduced in the carbonization process of alkaline activation remarkably promote the physicochemical properties of the biomass-derived porous carbon (PC), which can provide a favorable internal surface to load Ag3VO4 NPs. Subsequently, this electrochemical behavior of AVO/PC-modified glassy carbon electrode (AVO/PC/GCE) exhibits high sensitivity (4.95 mA mM−1 cm−2) and a varied linear detection range (1 μmol L−1 ≈ 1 mmol L−1), as well as reproducibility and stability for p-NP. Besides, the as-prepared AVO/PC demonstrates the enhanced photocatalytic degradation performance of rhodamine B (RhB), and the photocatalytic rate reaches to 94% in visible light irradiation. The findings should be useful for designing and constructing dual-purpose carbonaceous composite materials with potential applications in environmental monitoring and contaminant treatment.

Wind turbines and associated parts are susceptible to cyclic stresses, including torque, bending, and longitudinal stress, and twisting moments. Therefore, research on the resilience of dynamic systems under such high loads is crucial for design and future risk-free operations. The method described in this study is beneficial for multidimensional structural responses that have undergone sufficient numerical simulation or measurement. In contrast to established dependability methodologies, the unique technique does not need to restart the numerical simulation each time the system fails. Herein, it is demonstrated that it is also possible to accurately predict the probability of a system failure in the event of a measurable structural reaction. In contrast to well-established bivariate statistical methods, which are known to predict extreme response levels for 2D systems accurately, this study validates a novel structural reliability method that is particularly suitable for multidimensional structural responses. In contrast to conventional methods, the novel reliability approach does not invoke a multidimensional reliability function in the Monte Carlo numerical simulation case. As demonstrated in this study, it is also possible to accurately anticipate the likelihood of a system failure in the case of a measurable structural reaction.

TiO2–based photocatalysis system for splitting water into hydrogen offers a sustainable and green technology to produce clean hydrogen energy. However, pristine TiO2 still exists inherent shortcomings restricting its practical applications. Herein, the impact of postprocessing approaches of protonic titanate on engineering of oxygen vacancy and photocatalytic hydrogen evolution of TiO2−x is studied. Subsequently, interfacial cocatalysts are successfully involved in the optimized TiO2−x for enhanced photocatalytic hydrogen evolution. TiO2−x with the highest photocatalytic hydrogen evolution performance of 3112.09 μmol g−1 h−1, denoted as TiO2–C, is selected to adjust the interface with Cu and MoS2 respectively. Cu–TiO2–C and MoS2–TiO2–C composites are synthesized to enhance the separation ability of photogenerated electron-hole pairs and significantly improve the photocatalytic hydrogen evolution performance. The photocatalytic hydrogen evolution rates of 5 wt% Cu–TiO2–C and 40 wt% MoS2–TiO2–C are 9225.75 and 5765.48 μmol g−1 h−1, respectively. It is proved that different postprocessing methods can tune the content of oxygen vacancy in TiO2−x and regulate the photocatalytic hydrogen evolution performance of TiO2−x materials. The interface regulation of the cocatalyst also contributes to the separation of photogenerated electron-hole pairs and serves as active sites to enhance hydrogen evolution performance.

To date, organic–inorganic hybrid perovskite solar cells (PSCs) have reached a certified efficiency of 25.7%, showing their great potential in industrial commercialization. However, defects at the surface and grain boundaries hinder their device performance and long-term stability. Herein, long-chain dodecylammonium halides (DACl, DABr, and DAI) to treat the perovskite surface and improve the device performance are introduced. It is found that the three passivators can all form 2D perovskites but with different halide compositions. The DACl-treated perovskite forms a pure chloride DA2PbCl4 2D perovskite, while the DABr and DAI-treated surfaces form a pure iodide DA2PbI4 2D perovskite. Compared with the DA2PbI4 layer, it is found that the DA2PbCl4 passivation layer can more effectively passivate defects, improve carrier separation at the perovskite surface, and optimize the energy alignment between the perovskite film and hole transport layer. As a result, a champion power conversion efficiency of 23.91% is achieved for the DACl-treated PSCs. Moreover, the device maintains around 95% of its initial efficiency after 1000 h storage under relative humidity of 10% at 25 °C.

Multijunction solar cells combining III–V and Si materials can provide high photoelectric conversion efficiency. Two-terminal III–V//Si triple-junction solar cells with an efficiency of 35.9% have already been developed using metal–organic vapor-phase epitaxy and the direct wafer bonding technique. This study, however, proposes the low-cost fabrication of III–V solar cells using hydride vapor-phase epitaxy (HVPE). GaInAsP solar cells are fabricated using HVPE to apply to middle cells in III–V//Si triple-junction structures. By controlling the partial pressure of the precursors, the optimal bandgap energy of 1.5 eV is obtained for the HVPE-grown GaInAsP quaternary alloys. The 1.5 eV GaInAsP single-junction solar cells show higher open-circuit voltage than the HVPE-grown GaAs solar cells. The open-circuit voltage of the GaInAsP solar cells fabricated with a GaInAsP growth rate of 77.6 μm h−1 reaches 1.1 V upon the formation of the rear-heterojunction structure. In addition, the external quantum efficiency spectra of the HVPE-grown GaInP/GaInAsP dual-junction solar cells show that the 1.5 eV GaInAsP solar cells are superior to the GaAs solar cells in terms of current matching for subcells in the III–V//Si triple-junction structures.

Anode-free lithium metal batteries (AFLMBs) show promise as a means of further enhancing the energy density of current lithium-ion batteries, as they do not require conventional graphite anodes. The anode-free configuration, however, suffers from inferior chemical stability of the solid electrolyte interphase (SEI) layer and experiences inhomogeneous lithium deposition during charge/discharge processes, resulting in rapid capacity fading. To address these issues, a carbonized polydopamine (CPD) coating is applied to the copper current collector. The CPD-coated copper current collector promotes highly efficient and reversible lithium plating and stripping processes, resulting in a densely packed lithium deposition that significantly improves cycling stability. The anode-free full cell, consisting of CPD-coated copper current collector and a LiFePO4 cathode, demonstrates significantly improved electrochemical performance, with a capacity retention of more than 63% after 100 cycles at a current rate of 0.3C. The stability of the SEI layer and the presence of lithiophilic sites are verified through a range of techniques, including optical microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, chronoamperometry, and electrochemical impedance spectroscopy. Based on these collective findings, it can be inferred that the use of CPD coating provides a simple way to enhance the electrochemical performance of AFLMBs.

Nanoscale zero-valent iron (nZVI) has demonstrated high potential for the remediation of contaminated groundwater. Its lifetime is directly related to the hydrophobicity of nZVI. A promising approach to enhance the lifetime of nZVI is through sulfidation. Herein, the density functional theory (DFT) is applied to understand the impact of sulfidation on the hydrophobicity of stepped Fe surfaces. Adsorption properties of sulfur (S) at different coverages on the flat Fe(110) and stepped Fe(210) and Fe(211) surfaces are investigated. Sulfur has the stronger adsorption at a low surface coverage due to limited S–S repulsion. At the highest coverage (⊖ = 1 ML) on Fe(210) and Fe(211), the atoms at the step edges catalyze the formation of iron sulfides. The DFT results show surface hydrophobicity is mainly determined by the S coverage. At the low S coverage, the surface may become more hydrophilic due to the enhanced adsorption strength of water on the surface. However, an increase in the S coverage can efficiently block water adsorption, which is further evidenced by ab initio molecular dynamics (AIMD) results. The findings show that controlling S coverages is essential to engineer the hydrophobicity of nZVI surfaces for practical water remediation applications.

Alkali halide postdeposition treatments (PDTs) have become a key tool to maximize efficiency in Cu(InxGa1−x)Se2 (CIGS) photovoltaics. RbF PDTs have emerged as an alternative to the more common Na- and K-based techniques. This study utilizes temperature-dependent current–voltage (JVT) measurements to study a unique RbF PDT performed in a S atmosphere. The samples are measured before and after 6 months in a desiccator to study device stability. Both samples contain Na and K which diffuse from the soda–lime glass substrate. A reference sample and a RbF + S PDT sample both show the development of a rear contact barrier after aging. The contact barrier is higher for the RbF + S PDT sample, leading to decreased current in forward bias. Series resistance is also higher in the RbF + S PDT device which leads to lower fill factor. However, after aging the reference sample has a larger decrease in open-circuit voltage (VOC). Ideality factor measurements suggest Shockley–Read–Hall recombination dominates both samples. VOC versus temperature and a temperature-dependent activation energy model are used to calculate diode activation energies for each sample condition. Both techniques produce similar values that indicate recombination primarily occurs within the bulk absorber.

Inverted perovskite solar cells (PSCs) mainly adopt polytriarylamine (PTAA) for the hole transport material (HTM), which usually brings about inferior interfacial contact owing to their hydrophobicity, high-lying highest occupied molecular orbital energy level, and deficiency of passivation groups. Herein, a series of donor–π–acceptor (D–π–A) type small molecules is demonstrated based on 2,2′:6′,2″-terpyridine (TPy) as the acceptor moiety, benzene ring as the π-linker, and incorporating various donors to act as HTMs. These TPy-based molecules coated atop PTAA manipulate the energy level and surface wettability, but the incorporation of the phenoxazine (POZ) donor can be prominent for enhancing charge transport and defect passivation, thereby simultaneously addressing the above-mentioned issues. The highest power conversion efficiency of 22.36% can be achieved with an open-circuit voltage (VOC) of 1.15 V, a short-circuit current density (JSC) of 23.96 mA cm−2, and a fill factor (FF) of 81.16% for the optimized POZ-TPy-modified device. Moreover, the power PCE of a large POZ-TPy-modified device (1.96 cm2) can still reach more than 21%. These results are among one of the highest efficiencies for inverted PSCs, indicating the enormous potential of POZ-TPy HTM in future perovskite applications.

Phase-change materials are of great interest in solving mismatch between energy supply and demand. However, the vulnerability of solid–liquid phase-change materials to leakage during the phase-change process limits their development and application in practice. Herein, the enhancement of the shape stability of phase-change materials is achieved through an organic–inorganic composite. The mixture of phenolic resin and polyethylene glycol forms a homogeneous solution based on their excellent mutual solubility and is able to be adsorbed into the pores of the expanded graphite by means of a vacuum-impregnation strategy. The 3D cross-linked network structure of phenolic resin is formed within the pores of expanded graphite, enabling in situ encapsulation of polyethylene glycol. It is worth noting that the curing reaction of phenolic resin is able to be initiated by heating up without the addition of any curing agent and other auxiliary materials. A thermal conductivity enhancement of 20 times than that of polyethylene glycol is achieved along with a photothermal conversion efficiency of 63.72% and with a latent heat of 134.94 J g−1 without leakage.

Perovskite Photovoltaics

The transfer of energy through hydrides is of particular significance in the biocatalysis field. In nature, some enzymes proceed the cascaded hydride transfers via nicotinamide adenine dinucleotide (NADH) with high selectivity in mild conditions. Moreover, chemical strategies are developed to transfer hydrides in vitro for NADH regeneration, which often require noble metals as mediators to promote the regioselectivity of NADH reduction to bioactive 1,4-NADH. Recently, the Mo3+ hydride generated in amorphous molybdenum sulfide under cathodic potential can work for selective hydrogenation of NAD+ to 1,4-NADH, opening promising prospects for sustainable biocatalysis.

Li-ion batteries (LIBs) have been widely used in portable electronic devices, the transportation sector, and grid storage. However, LIB anodes are restricted to carbon-based materials limiting their energy density. Recently, the use of metallic Li as the anode in Li-metal (LMBs) and solid-state (LMSSBs) batteries has gained attention due to the high energy densities it can provide. Herein, the research progress in the field to derive a broad picture of the technologies relying on Li metal as the anode is critically assessed. It is essential to understand the Li plating and stripping processes in terms of fundamental electrochemical and physical mechanisms to address the challenges of employing metallic Li. Anode-free Li-metal batteries (AFLMBs) and anode-free solid-state batteries (AFSSBs) are the most attractive systems discussed in this review. AFLMBs are highly studied, but safety concerns due to Li dendrite growth and side reactions between plated Li metal and liquid electrolyte are some key challenges yet to be resolved. AFSSBs are the ultimate goal in this field, as utilizing a solid-state electrolyte (SSE) can prevent dendrites at moderate charging rates and realize the potential of the anode-free battery. However, the general problems with the use of SSEs remain and require substantial research efforts.

Herein, the thermoelectric characteristics of polytriarylamine-Lewis acid complex films were investigated by employing a horizontal device structure. Poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (PolyTPD) is doped with tris(pentafluorophenyl)borane (BCF) via Lewis acid–base reactions by varying the BCF molar ratio (0–300 mol%). The resulting PolyTPD:BCF films are spun on glass substrates and silver electrodes are deposited leading to the horizontal type of organic thermoelectric devices (OTEDs). The OTEDs with the PolyTPD:BCF films are examined by varying temperature differences up to 45 K between two silver electrodes directly contacting hot/cold sources. Both device current and voltage are proportionally increased with the temperature difference, leading to higher powers at larger temperature differences, irrespective of BCF molar ratio. However, the highest current is achieved at 50 mol% owing to the highest electrical conductivity, even though the device voltage is slightly lower at 50 than 20 mol%. The origin of high electrical conductivity is assigned to the formation of radical cations in PolyTPD chains by BCF doping, which is influenced by the reaction time. The device current can be also generated by the illumination of IR radiation (noncontact mode) that is away from the OTEDs with the PolyTPD:BCF films.

Solar-driven photoelectrochemical (PEC) water splitting cell fabricated using colloidal quantum dots (QDs) is deemed as low-cost and high-efficiency solar-to-fuel conversion systems for future carbon neutrality. However, current QDs-based PEC technologies are still hindered by several critical restrictions including the sluggish water oxidation kinetics and the frequent use of highly toxic QDs (e.g., Pb, Cd-chalcogenides) as well as co-catalysts, thus limiting their prospective commercial developments. Herein, the optoelectronic properties of heavy metal-free InP/ZnSe core/shell QDs are tailored by introducing the interfacial GaP layers with variable thicknesses. As-prepared InP/GaP/ZnSe core/shell QDs are used to sensitize TiO2 film as photoanodes for PEC water oxidation, showing an unprecedented photocurrent density of 4.1 mA cm−2 at 1.23 V versus reversible hydrogen electrode with excellent durability under one sun AM 1.5 G illumination. It is demonstrated that engineering the thickness of the interfacial GaP layer enables optimized optical properties and can introduce appropriate intermediate energy levels to promote the charge extraction from the InP core to the ZnSe shell for enhanced PEC water oxidation efficiency. This study paves the way for interfacial engineering of “green” core/shell QDs to realize cost-effective, environment-friendly, high-performance, and co-catalyst-free QDs-based PEC water splitting system.

The efficient conversion and utilization of CO2 is imminent due to the increase of global CO2 emissions year by year, so the strategy of electrocatalytic CO2 reduction to high value-added chemicals comes into being. The CO2 reduction reaction (CO2RR) can yield diversified products, including C1 (like CO, CH4, etc.), C2 (like C2H4, C2H5OH, etc.), and other multicarbon compounds. Thereinto, selective transformation to C2 compounds is relatively significative by reason of high industrial value but being greatly challenging, particularly involving complex CC coupling. Herein, the reaction mechanisms of several C2 products (including C2H4, C2H5OH, and H2C2O4) and corresponding latest research progress are summarized and discussed. Besides, N atoms, from N2, nitrates, and nitrites, are integrated into CO2RR to yield nitrogen-containing organics (like urea, amides, and amines), broadening the application field of CO2RR. Therefore, the part on the electrocatalytic coupling of CO2 and nitrogen sources (including N2, NO3−, NO2−) by CN bonds is also delved in this review, including recent advances, reaction mechanisms, and related key intermediates.

Nickel selenide is an emerging electrode material for high-performance hybrid supercapacitors; however, poor electrical conductivity and sluggish ion kinetics limit its application. Herein, a unique architecture by decorating NiSe nanoparticles on reduced graphene oxides (rGO) is developed. The synergistic effect of NiSe and rGO facilitated by the optimized addition of rGO results in significant improvement in the electrochemical performance. The physicochemical characterizations suggest that the enhancement can be attributed to increased interfacial interaction and access to the electrochemically active sites. The NiSe/rGO hybrid delivers a specific capacity of 351 mAh g−1 at 1 A g−1, which is significantly higher than that for bare NiSe. Later, the hybrid supercapacitor based on NiSe/rGO hybrid as positive and activated carbon as negative electrode delivers a maximum energy density of 49.6 Wh kg−1 at a power density of 748.37 W kg−1. In addition, the device shows good cyclic stability of 83.3% over 5000 cycles. Thus, an innovative approach to the development of high-performance hybrid supercapacitors is offered.

Electrocatalytic CO2 reduction reaction (CRR) is a promising way to convert carbon dioxide (CO2) into value-added hydrocarbons to alleviate the ever-increasing environmental problem and accelerate the realization of carbon cycling. Cost-effective and stable electrocatalytic materials with low overpotential, superior selectivity, excellent activity and great stability are critically important to achieve such a target. Cu-based electrocatalysts are promising candidates for electrochemical CRR due to their versatile abilities of converting CO2 into various products. This review analyzes and summarizes the current progress in utilization of Cu-based catalytic materials for electrochemical CRR. Monometallic, bimetallic, trimetallic, and multimetallic Cu-based electrocatalysts with variable elemental compositions and tunable morphologies, including Cu nanowires, Cu nanocubes (NCs), Cu porous structures, Cu-based alloys, Cu-oxide/hydrogen oxide, Cu single atoms, and 2D substrate-supported Cu electrocatalysts for CRR, are surveyed. Substantial advances in overcoming the existing bottlenecks of eletrocatalysts and effectively improving CRR performance of Cu-based electrocatalysts for future applications are systematically discussed. Challenges and perspectives of Cu-based electrocatalytic materials for CRR are also offered, which may shed light on further development of Cu-based electrocatalysts with superior performance. It is anticipated that this review will provide a valuable insight into the rational design and synthesis of highly efficient Cu-based electrocatalysts for large-scale CRR utilization.

A phosphomolybdic acid (PMA)-doped poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) hole transporting layer (HTL) is developed to effectively optimize the anode interface of inverted organic photovoltaic (OPV) devices. Since a deep-lying work function of HTL is in favor of reducing the interfacial barrier for hole transporting, superior power conversion efficiencies (PCE) of 9.22% and 10.8% are achieved in fullerene-based and nonfullerene-based devices in inverted architecture. Thus-prepared OPV devices also exhibit excellent photostability and retain 85% of the initial PCE after 1000 h of irradiation under 100 mW cm−2 irradiation. The overall result suggests the practicability and mitigation of efficiency loss when replacing the conventional PEDOT:PSS with PMA-doped PEDOT:PSS as HTL to fabricate highly efficient, inverted OPV devices.