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Silicon-flexible carbon composites can achieve binder-free application and solve the problem of silicon expansion during cycles. The effective loading and dispersion of silicon onto carbon play an important role in improving the performance of anode materials. Herein, surface engineering of the hole-opening process was successfully achieved before the deposition of silicon. This resulted in fine holes on the carbon cloth, increasing the specific surface area to provide abundant confined spaces for dispersing nano-silicon. A composite structure was formed and structurally optimized by depositing an ultra-thin silicon layer in the holes of mesoporous carbon fiber cloth (DTSi/CC), improving the conductivity of the material, increasing the migration rate of lithium ions, and inhibiting the volume expansion of the anode material during the cycles. At 100 mA g–1, the fabricated half-cells achieved a reversible capacity of 1457 mA h g–1 and retained 70.9% initial capacity after 100 cycles. Even when the current density was increased to 1.0 A g–1, they boasted a capacity of 1037 mA h g–1 and had 76.8% capacity retention after 500 cycles. Free of binders and conductive additives, the DTSi/CC composite was directly used as the anode, exhibiting superior properties with high reversible specific capacity, excellent cyclic performance, and good rate capability. This study provides a straightforward, effective route to obtain high-performance silicon-based anode materials for lithium-ion batteries.

With rapid economic development, utilization of energy storage is increasingly important. Carbon materials derived from biomass are widely applied in energy storage systems due to their inexpensive and environmentally friendly nature. Compared to other advanced anode materials that have been explored, biomass carbon materials have high specific surface areas, adjustable porous structures, and heteroatoms that facilitate ion transfer and diffusion. To date, a series of porous biomass-derived carbon materials prepared through various methods have been used as anode electrodes of secondary batteries which greatly promoted their capacities. In this paper, we summarize the morphology and pore structure of biomass-derived materials from different precursors and discuss the electrochemical performance of secondary batteries (LIBs, SIBs, KIBs and ASSLMBs) equipped with biomass-derived carbon materials including monomers and composites as anode electrodes. Current research challenges along with future prospects for carbon-based electrode materials to improve secondary battery energy storage performance are emphasized.

During the last years, lead perovskites have achieved high power conversion efficiency of 23%. However, their long-term stability and toxicity are still crucial issues that required attention. In this study, we are the first to report on the synthesis and characterizations of a new lead-free mixed halide-chalcogenide perovskite MABiI2S (MBIS), and have determined its physical and optical properties by various testing methods. The MBIS has a low bandgap of 1.52 eV, with an extended absorption onset up to over 1000 nm. Solar cells fabricated with the MBIS were inspected and device improvements were applied.

In this work, a simple interface engineering process for SnO2 electron selective layer (ESL) surface passivation employing a SnCl2 solution is introduced, which has successfully reduced the energy loss for a high open-circuit voltage (Voc) output and consequently improved the performance of all-inorganic CsPbIBr2 perovskite solar cells (PSCs). It was found that surface passivation can effectively suppress the recombination process at the interface between the perovskite and SnO2 due to higher recombination resistance. The shorter PL decay time is attributed to the excellent electron extraction from the perovskite film. After optimizing surface passivation, the power conversion efficiency (PCE) was enhanced from 4.73% to 7.00% and a high Voc of 1.31 V was achieved, which is one of the highest Voc values reported for inorganic Cs-based PSCs. More importantly, the passivated SnO2 based device retains 95.5% of its initial performance at 90 °C in air without encapsulation. This work provides a simple and efficient interface engineering method to improve the Voc and efficiency of all-inorganic PSCs.

Recently, sodium‐ion batteries have attracted great attention, owing to the rich resource and low cost. In the present work, a feather‐like MnO2 nanostructure was prepared directly on carbon paper by using a rapid and simple hydrothermal route for the first time. The formation mechanism was proposed by investigating the intermediate products during the reaction. When applied as an anode for a sodium‐ion battery, the feather‐like MnO2 nanostructure on carbon paper exhibited a high discharge capacity, good rate reversibility, and long‐term cycling stability. A high specific capacity of approximately 300 mAh g−1 could be obtained even after cycling 400 times with a current density of 0.1 A g−1. Furthermore, the Na+ storage mechanism of MnO2 on carbon paper in the sodium‐ion battery was also investigated in this work. Such high performance can be attributed to the porous structure of the substrate and high specific surface area of the feather‐like nanostructure.

TiO2 is commonly used as an electron-transporting material in perovskite photovoltaic devices due to its advantages, including suitable band gap, good photoelectrochemical stability, and simple preparation process. However, there are many oxygen vacancies or defects on the surface of TiO2 and thus this affects the stability of TiO2-based perovskite solar cells under UV light. In this work, a thin (monolayer) SbI3 modification layer is introduced on the mesoporous TiO2 surface and the effect at the interface between of TiO2 and perovskite is monitored by using a quartz crystal microbalance system. We demonstrate that the SbI3-modified TiO2 electrodes exhibit superior electronic properties by reducing electronic trap states, enabling faster electron transport. This approach results in higher performances compared with electrodes without the SbI3 passivation layer. CH3NH3PbI3 perovskite solar cells with a maximum power conversion efficiency of 17.33% in air, accompanied by a reduction in hysteresis and enhancement of the device stability, are reported.

Despite the high efficiency of MAPbI3 perovskite solar cells, the long term stability and degradation in humid atmosphere are issues that still needed to be addressed. In this work, magnesium iodide (MgI2) was first successfully used as a dopant into MAPbI3 perovskite prepared in humid air atmosphere. Mg doping decreased the valence band level, which was determined from photoelectron yield spectroscopy. Compared to the pristine MAPbI3 perovskite film, the 1.0% Mg-doped perovskite film showed increased crystal grain size and formation of pinhole-free perovskite film. Performance of the solar cell was increased from 14.2% of the doping-free solar cell to 17.8% of 1.0% Mg-doped device. Moreover, 90% of the original power conversion efficiency was still retained after storage in 30–40% relative humidity for 600 h.

Bismuth‐based solar cells have been under intensive interest as an efficient non‐toxic absorber in photovoltaics. Within this new family of semiconductors, we herein report a new, long‐term stable copper bismuth iodide (CuBiI4). A solutionprocessed method under air atmosphere is used to prepare the material. The adopted HI‐assisted dimethylacetamide (DMA) co‐solvent can completely dissolve CuI and BiI3 powders with high concentration compared with other organic solvents. Moreover, the high vapor pressure of tributyl phosphate, selected for the solvent vapor annealing (SVA), enables complete low‐temperature (≤70°C) film preparation, resulting in a stable, uniform, dense CuBiI4 film. The average grain size increases with the precursor concentration, greatly improving the photoluminescence lifetime and hall mobility; a carrier lifetime of 3.03 ns as well as an appreciable hall mobility of 110 cm2V−1s−1 were obtained. XRD illustrates that the crystal structure is cubic (space group Fd3m) and favored in the [111] direction. Moreover, the photovoltaic performance of CuBiI4 was also investigated. A wide bandgap (2.67 eV) solar cell with 0.82% power conversion efficiency is presented, which exhibits excellent long‐term stability over 1008 h under ambient conditions. This air‐stable material may give an application in future tandem solar cells as a stable short‐wavelength light absorber.

High-efficiency perovskite solar cells (PSCs) need to be fabricated in the nitrogen-filled glovebox by the atmosphere-controlled crystallization process. However, the use of the glovebox process is of great concern for mass level production of PSCs. In this work, notable efficient CH3NH3PbI3 solar cells can be obtained in high humidity ambient atmosphere (60–70% relative humidity) by using acetate as the antisolvent, in which dependence of methyl, ethyl, propyl, and butyl acetate on the crystal growth mechanism is discussed. It is explored that acetate screens the sensitive perovskite intermediate phases from water molecules during perovskite film formation and annealing. It is revealed that relatively high vapor pressure and high water solubility of methyl acetate (MA) leads to the formation of highly dense and pinhole free perovskite films guiding to the best power conversion efficiency (PCE) of 16.3% with a reduced hysteresis. The devices prepared using MA showed remarkable shelf life stability of more than 80% for 360 h in ambient air condition, when compared to the devices fabricated using other antisolvents with low vapor pressure and low water solubility. Moreover, the PCE was still kept at 15.6% even though 2 vol % deionized water was added in the MA for preparing the perovskite layer.

Perovskite solar cells have attracted considerable attention owing to their easy and low‐cost solution manufacturing process with high power conversion efficiency. However, the fabrication process is usually performed inside a glovebox to avoid moisture, as organometallic halide perovskites are easily dissolved in water. In this study, we propose a one‐step fabrication of high‐quality MAPbI3 perovskite films in around 50% relative humidity (RH) humid ambient air by using diethyl ether as an antisolvent and methanol as an additive into this antisolvent. Because of the presence of methanol, the water molecules can be efficiently removed from the gaps of the perovskite precursors and the perovskite film formation can be slightly controlled, leading to pinhole‐free and low roughness films. Concurrently, methanol can be used to tune the DMSO ratio in the intermediate perovskite phase to regulate perovskite formation. Planar solar cells fabricated by using this method exhibited the best efficiency of 16.4% with a reduced current density–voltage hysteresis. This efficiency value is approximately 160% higher than the devices fabrication by using only diethyl ether treatment. From the impedance measurement, it is also found that the recombination reaction is suppressed when the device is prepared with methanol additive in the antisolvent. This method presents a new path for controlling the growth and morphology of perovskite films in humid climates and laboratories with uncontrolled environments.

Pt-based alloys have been explored as the most promising cathode catalyst for fuel cells due to their excellent electrocatalytic activity in oxygen reduction reaction (ORR). However, the long-term performance of Pt-based alloys is compromised owing to the de-alloying behavior under the corrosive circumstance. More importantly, the complicated synthesized methods have hindered their further practical application. In this report, a facile and effective operating conditions-assisted method has been developed to synthesize the stable hexagonal nanoplates PtFe alloy with a high electrocatalytic activity. In the three prepared PtM (M: Fe, Co, Ni) alloy samples, the PtFe alloy exhibits a superior catalytic activity, which improves by about 100 and 178?mV for half-wave potential in alkaline and acidic medium with the same Pt-loading amount, respectively. In addition, the PtFe alloy catalyst exhibits an electrochemical stability, compared to the conventional carbon-supported Pt catalysts. In view of the advantages of the facile operating preparation and the excellent electrocatalytic performance, we believe that the hexagonal nanoplates PtFe alloy holds great application as a promising electrocatalyst in polymer electrolyte membrane fuel cell (PEMFC).

For the first time, WO2.72 nanowires were in-situ grown on carbon cloth by a simple solvothermal reaction. The nanowire WO2.72/carbon cloth (NW WO2.72/CC) electrode showed good electrochemical performance with specific capacitance (C s) reaching up to 398 F g-1 at a current density of 2 A g-1. The capacitance of 240 F g-1 was retained at a high current density of 16 A g-1. To further evaluate the energy storage performance, flexible asymmetric supercapacitors (FASCs) were fabricated using the activated carbon/carbon cloth (AC/CC) as negative electrode and NW WO2.72/CC as positive electrode, respectively. The FASCs delivered a high energy density of 28 Wh kg-1 at a power density of 745 W kg-1 and 13 Wh kg-1 even at a high power density of 22.5 kW kg-1. More impressively, 81% of the specific capacitance of the FASCs was retained after 10,000 cycles, indicating excellent cycle stability. This work indicates the NW WO2.72/CC holds a great potential for application in energy storage devices.

Organic?inorganic halide perovskite solar cells (PSCs) have attracted much attention in recent years and their power conversion efficiency (PCE) has rapidly improved from 3.8% to 22.7%. However, the commonly used electron selective layer (ESL), TiO2, requires a high-temperature post-treatment during its preparation process, which is not compatible with flexible PSCs on plastic substrates. Moreover, it is energy intensive and not suitable for the low-cost mass production of PSCs. Developing low-temperature processable ESLs can solve these problems and realize the all-low-temperature fabrication of PSCs. Therefore, in this review, the current progress in low-temperature processed ESLs, especially non-TiO2 inorganic and organic materials and quantum dots (QDs), such as SnO2, ZnO, WOx, CeOx, Nb2O5, In2O3, CdS, Bi2S3, In2S3, Zn2SnO4, fullerene, non-fullerene, CdSe QDs, etc., is summarized. Their preparation methods, properties and applications for use in PSCs are highlighted. Several results obtained by our group are also included. These low-temperature processed ESLs will provide more possibilities for implementing the all-low-temperature fabrication of PSCs with high performances.

Electrode material based on a novel core-shell structure consisting of NiCo2S4 (NCS) solid fiber core and MnS (MS) sheet shell (NCS@MS) in situ grown on carbon cloth (CC) has been successfully prepared by a simple sulfurization-assisted hydrothermal method for high performance supercapacitor. The synthesized NiCo2S4@MnS/CC electrode shows high capacitance of 1908.3 F g-1 at a current density of 0.5 A g-1 which is higher than those of NiCo2S4 and MnS at the same current density. A flexible all-solid-state asymmetric supercapacitor (ASC) is constructed by using NiCo2S4@MnS/CC as positive electrode, active carbon/CC as negative electrode and KOH/poly (vinyl alcohol) (PVA) as electrolyte. The optimized ASC shows a maximum energy density of 23.3 Wh kg-1 at 1 A g-1, a maximum power density of about 7.5 kw kg-1 at 10 A g-1 and remarkable cycling stability. After 9000 cycles, the ASC still exhibited 67.8% retention rate and largely unchanged charge/discharge curves. The excellent electrochemical properties are resulted from the novel core-shell structure of the NiCo2S4@MnS/CC electrode, which possesses both high surface area for Faraday redox reaction and superior kinetics of charge transport. The NiCo2S4@MnS/CC electrode shows a promising potential for energy storage applications in the future.

A Ni3S2/MnS composite with unique 3-D morphology was synthesized by a novel method consisting of etching and pre-oxidation of Ni foam followed by in situ hydrothermal method. The etching process created a flower-like structure with the Ni foam which was not only used as a substrate but also providing Ni source for subsequent growth of Ni3S2 and Ni3S2/MnS composite. The synthesized material showed hierarchical structure consisting of porous Ni3S2 which was coated with vertically grown MnS nanorods. The superior morphology enables the access of more active sites in the electrochemical charge/discharge process. In the meantime, the charges involved in redox reaction can be effectively transferred via Ni3S2 with relatively high conductivity to Nickel foam substrate, which improved the availability of MnS. Therefore, when the Ni3S2/MnS composite was used as a supercapacitor electrode, it showed a remarkable electrochemical performance of 6.70 mAh cm?2 which is over two-fold higher than that of the Ni3S2 (3.15 mAh cm?2) and MnS (2.34 mAh cm?2) at current density of 2 mA cm?2, respectively. Impressively, the specific capacity of Ni3S2/MnS still retained 6.41 mAh cm?2 with the capacity retention of 96.5% even after 1000 cycles. Further, the electrochemical properties of asymmetric supercapacitors (ACSs) deliver a maximum energy density of 0.47 mWh cm?2 at power density of 10 mW cm?2, together with 82.1% retention after long-term test.

Active composite layers of bismuth triiodide (BiI3) and lead-free (CH3NH3)3Bi2I9 (MBI) perovskite were prepared using a simple chemical solution method under ambient conditions for thin-film solar cells. Results of X-ray diffraction and scanning electron microscopy indicated that the crystallization and surface morphologies of the composite films varied with perovskite contents. Multi-absorption was observed in the composite films due to the bandgap difference between BiI3 and MBI perovskite. Moreover, band bending at the BiI3-perovskite interfaces resulted in the realignment of energy levels in the composite films, and this phenomenon was beneficial to the efficient injection of excited electrons from the active layers into the TiO2 layers. Accordingly, due to the optimized crystallization and realigned energy level, when 20% of MBI perovskite was introduced into the active layers, the open-circuit voltage obviously increased from 0.44 V to 0.57 V in the (BiI3)0.8(MBI)0.2 composites solar cells, enhancing their power conversion efficiency by 67% compared with that in pure BiI3 solar cell. This study developed a new route for designing more efficient lead-free solar cells.

Despite the remarkable performance of organometallic halide perovskite solar cells (PSCs), their ultimate stability is still a major issue that inhibits the commercialization of this eminent technology. Herein, melamine hydroiodide (MLAI) is added to function methyl ammonium (CH3NH3+, MA+) lead iodide perovskite for fabricating structured perovskite with enhanced photovoltaic performance and stability in the harsh ambient atmosphere (35 °C, 60–70% relative humidity). Nearly no new phase formed even incorporated 25 mol.% MLAI induces the strain in the perovskite crystal structure. The MLAI‐structured perovskite film shows a denser and smoother surface than the pristine MAPbI3 perovskite. Planar PSCs based on 2 mol.% MLAI‐functionalized perovskite show 17.2% power conversion efficiency with nearly no hysteresis which is much higher than pristine MAPbI3 PSCs. Most importantly, the solar cell devices based on 2 mol.% MLAI‐functionalized perovskite still retain over 90% of the initial performance after being kept in ambient atmosphere for more than 560 h without encapsulation.

In recent decades, catalytic reduction of CO2 is a hot topic in the research field of electrocatalysis. Copper is the only metal catalyst capable of producing multiple carbon (C2+) products in electrocatalytic CO2 reduction (ECR), however, there are still many challenges such as low selectivity, serious hydrogen evolution (HER) and poor stability. So far, various synthesis methods have been developed for Cu-based catalysts. Compared with ordinary chemical synthesis, electrochemical method has the advantages of simple process, controllable conditions, good safety and eco-friendly. In this review, the recent progress in synthesizing different types of Cu-based catalysts by means of the electrochemical method are comprehensively reviewed. The engineering strategies and the effects of the key preparation conditions on the catalytic performance of CO2 electroreduction for C2+ products are discussed in details. Besides, copper-based catalysts synthesized by electrochemical methods combined with the ordinary methods (wet chemical methods, plasma activated methods and other methods) were also outlined. Finally, the development potential of electrochemical synthesis for Cu-based catalysts are recommended, which provides a direction for the future development of Cu-based catalysts with low cost and high ECR performance.

For the 1st time, nonstoichiometric WO2.72 was used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). O-vacancy-rich WO2.72 nanorod bundles with notable catalytic activity for triiodide and thiolate redn. were prepd. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) with WO2.72 nanorod bundles as CEs are superior compared with those of the WO3-based cells, and nearly the same as those of the precious metal Pt-based cells. In a noncorrosive org. redox couple, the performance of WO2.72 CEs is better than that of Pt and WO3 CEs in DSSCs.

The authors presented the solid-state synthesis of ZnO nanostructured building blocks for the fabrication of high efficiency quasi-solid Dye-Sensitized Solar Cells (DSSCs). Photoanodes composed of tiny nanosheets were sponge-like in construction, ensuring a high optical d. and better connections of the 2 sep. channels, 1 for the electron transport in the ZnO network and the other for the diffusion of redox couples in the electrolyte. The authors systematically revealed the effects of thermal-treating temps. on the microstructures and the elec. properties of the photoanode films as well as their performances in quasi-solid DSSCs. Also, by using a polymer gel electrolyte, the authors provided an effective strategy to simultaneously improve the photovoltaic conversion efficiency (PCE) and longterm durability. With the low-temp. treated photoanode films, devices achieved enhanced PCEs up to 6.46%, the highest for the ZnO quasi-solid DSSCs.

Zinc oxide (ZnO) hierarchical structures (HSs) have recently demonstrated notable photochem. and photovoltaic performances attributed to their nano/micro combined architectures. In this study, ZnO HSs were synthesized at room temp. using ultrarapid sonochem. This novel approach can effectively overcome deficiencies in the synthesis via traditional direct pptn. by promoting nucleation and accelerating diffusion. Only 15 min was needed to complete the formation of highly crystd. and uniformed HSs consisting of interconnected monocryst. nanosheets using sonochem. The formation of HSs through in situ observations was interpreted using a new mechanism based on oriented attachment and reconstruction. In the nonequil. synthesis system, thicker, porous, and coarse crystd. ZnO sheets were first constructed via oriented attachment of small-sized nanocrystals. After reconstruction, ultrathin, integrated, and monocryst. nanosheets were obtained. According to the two-dimensional nanosheets to three-dimensional HSs, the formation was much more sophisticated because repeated and parallel heterogeneous oriented attachments with reconstructions dominated the final morphologies of the HSs. The relationships between synthetic conditions and HSs structures were established. Based on the photoanodes in dye-sensitized solar cells (DSCs), the performances of these differently structured HSs were tested. HSs with densely assembled nanosheets exhibited better performances in photoelec. conversions. Systematic investigations were also carried out by selecting two representative HSs to demonstrate the crit. factors governing the optical and elec. properties of photoanodes. Finally, under AM 1.5 and 100 mW.cm-2 light irradn., high photoelec. conversion efficiencies of up to 6.42% were achieved. These results established a new record for quasi-solid ZnO-based DSCs.

TiC has been used as a counter electrode catalyst in place of Pt for triiodide redn. in dye-sensitized solar cells. Its catalytic activity can be comparable to that of Pt. The effect of the thickness of the TiC layer on the performance of the dye-sensitized solar cells was investigated by electrochem. impedance spectroscopy, cyclic voltammetry, and Tafel polarization measurements. We found that as the film thickness increased, the fill factor and short-circuit c.d. increased, which led to improved power conversion efficiency. When the TiC film was thicker than 20 μm, however, no significant continuous improvement in the catalytic activity was obsd. A high power conversion efficiency of 6.46% was obtained for the dye-sensitized solar cell by using a TiC counter electrode at the optimized film thickness, a value similar to that obtained with a Pt counter electrode.

We demonstrated that extracts from sea tangle can serve as a sensitizer, redox couple, as well as a counter electrode material, or even can be fabricated into an "all-natural solar cell". Especially, the carbon counter electrode from sea tangle has achieved a comparable performance with Pt, favorable for the cost-reduction of DSCs.