Ultralow-voltage hydrogen production and simultaneous Rhodamine B beneficiation in neutral wastewater

Electrocatalytic water splitting for hydrogen production is hampered by the sluggish oxygen evolution reaction(OER)and large power consumption and replacing the OER with thermodynamically favourable reactions can improve the energy conversion efficiency.Since iron corrodes easily and even self-corrodes to form magnetic iron oxide species and generate corrosion currents,a novel strategy to integrate the hydrogen evolution reaction(HER)with waste Fe upgrading reaction(FUR)is proposed and demonstrated for energy-efficient hydrogen production in neutral media.The heterostructured MoSe_(2)/MoO_(2) grown on carbon cloth(MSM/CC)shows superior HER performance to that of commercial Pt/C at high current densities.By replacing conventional OER with FUR,the potential required to afford the anodic current density of 10 m A cm^(-2)decreases by 95%.The HER/FUR overall reaction shows an ultralow voltage of 0.68 V for 10 m A cm^(-2)with a power equivalent of 2.69 k Wh per m^(3)H_(2).Additionally,the Fe species formed at the anode extract the Rhodamine B(Rh B)pollutant by flocculation and also produce nanosized magnetic powder and beneficiated Rh B for value-adding applications.This work demonstrates both energy-saving hydrogen production and pollutant recycling without carbon emission by a single system and reveals a new direction to integrate hydrogen production with environmental recovery to achieve carbon neutrality.

A flame-retardant binder with high polysulfide affinity for safe and stable lithium–sulfur batteries

Lithium-sulfur(Li-S) batteries have shown promises for the next-generation, high-energy electrochemical storage, yet are hindered by rapid performance decay due to the polysulfide shuttle in the cathode and safety concerns about potential thermal runaway. To address the above challenges, herein, we show a flame-retardant cathode binder that simultaneously improves the electrochemical stability and safety of batteries. The combination of soft and hard segments in the polymer framework of binders allows high flexibility and mechanical strength for adapting to the drastic volume change during the Li(de)intercalation of the S cathode. The binder contains a large number of polar groups, which show the high affinity to polysulfides so that they help to anchor active S species at the cathode. These polar groups also help to regulate and facilitate the Li-ion transport, promoting the kinetics of polysulfide conversion reaction. The binder contains abundant phosphine oxide groups, which, in the case of battery's thermal runaway, decompose and release PO· radicals to quench the combustion reactions and stop the fire. Consequently, Li-S batteries using the new cathode binder show the improved electrochemical performance, including a low-capacity decay of 0.046% per cycle for 800 cycles at 1 C and favorable rate capabilities of up to 3 C. This work offers new insights on the practical realization of high-energy rechargeable batteries with stable storage electrochemistry and high safety.

Latest progress on fully non-fused electron acceptors for high-performance organic solar cells

Benefitting from the development of non-fullerene acceptors(NFAs),remarkable advances have been achieved with the power conversion efficiency(PCE)exceeding 19%over the last few years.However,the major achievement comes from fused ring electron acceptors(FREAs)with complex structures,leading to high cost.Hence,it is urgent to design new materials to resolve the cost issues concerning basic commercial requirements of organic solar cells.Recently,great progress has been made in fully non-fused ring electron acceptors(NFREAs)with only single-aromatic ring in the electron-donating core,which might achieve a fine balance between the efficiency and cost,thus accelerating the commercial application of organic solar cells.Therefore,this article summarizes the recent advances of fully NFREAs with efficiency over 10%,which may provide a guidance for developing the cost-effective solar cells.

Efcient soluble PTCBI‑type non‑fullerene acceptor materials for organic solar cells

Single perylene diimide(PDI)used as a non-fullerene acceptor(NFA)in organic solar cells(OSCs)is enticing because of its low cost and excellent stability.To improve the photovoltaic performance,it is vital to narrow the bandgap and regulate the stacking behavior.To address this challenge,we synthesize soluble perylenetetracarboxylic bisbenzimidazole(PTCBI)molecules with a bulky side chain at the bay region,by replacing the widely used“swallow tail”type alkyl chains at the imide position of PDI molecules with a planar benzimidazole structure.Compared with PDI molecules,PTCBI molecules exhibit red-shifted UV–vis absorption spectra with larger extinction coefcient,and one magnitude higher electron mobility.Finally,OSCs based on one soluble PTCBI-type NFA,namely MAS-7,exhibit a champion power conversion efciency(PCE)of 4.34%,which is signifcantly higher than that of the corresponding PDI-based OSCs and is the highest PCE of PTCBI-based OSCs reported.These results highlight the potential of soluble PTCBI derivatives as NFAs in OSCs.

Self-powered electrochromic devices with tunable infrared intensity

Triboelectric nanogenerator(TENG) is an efficient way to convert ambient mechanical energy into electricity to power up portable electronics.In this work,a flexible infrared electrochromical device(IR-ECD)with stable performances was assembled with a TENG for building self-powered infrared detector with tunable intensity.As driven by TENG,the electrochromic device could be operated in the mid-IR region due to the reversible electrochromic reactions.An average infrared reflectance contrast of 46% was achieved in 8–14 lm regions and as well a clear thermal image change can be observed.This work indicates that the TENG-driven infrared electrochromical device has potential for use in self-powered camouflage and thermal control.

Se-Ni Se_(2) hybrid nanosheet arrays with self-regulated elemental Se for efficient alkaline water splitting

Understanding the catalytic mechanism of non-noble transition metal electrocatalysts is crucial to designing high-efficiency,low-cost,and durable alternative electrocatalysts for water splitting which comprises the hydrogen evolution reaction(HER) and oxygen evolution reaction(OER).In this work,Se-NiSe_(2) hybrid nanosheets with a self-regulated ratio of ionic Se(I-Se) to elemental Se(E-Se) are designed on carbon cloth by solution synthesis and hydrothermal processing.The effects of the I-Se/E-Se ratios on the electrocatalytic characteristics in HER and OER are investigated systematically both experimentally and theoretically.The optimized bifunctional electrocatalyst needs overpotentials of only 133 mV to deliver an HER current density of 10 mA cm^(-2) and 350 mV to generate an OER current density of 100 mA cm^(-2) in1.0 mol L^(-1) KOH.Based on the density-functional theory calculation,surface-adsorbed E-Se is beneficial to optimizing the electron environment and the adsorption/desorption free energy of hydrogen/water of the hybrid catalyst,consequently facilitating the electrocatalytic water splitting process.There is a proper I-Se/E-Se ratio to improve the catalytic activity and kinetics of the reaction and the optimized E-Se adsorption amount can balance the interactions between I-Se and E-Se,so that the catalyst can achieve appropriate Se-H binding and active site exposure for the excellent electrocatalytic activity.To demonstrate the practicality,the assembled symmetrical device can be powered by an AA battery to produce hydrogen and oxygen synchronously.Our results provide a deeper understanding of the catalytic mechanism of transition metal selenides in water splitting and insights into the design of high-efficiency and low-cost electrocatalysts in energy-related applications.

Effects of subtle change in side chains on the photovoltaic performance of small molecular donors for solar cells

Small-molecule organic solar cells(SMOSCs)have attracted considerable attention owing to the merits of small molecules,such as easy purification,well-defined chemical structure.To achieve high-performance SMOSCs,the rational design of well-matched donor and acceptor materials is extremely essential.In this work,two new small molecular donor materials with subtle change in the conjugated side thiophene rings are synthesized.The subtle change significantly affects the photovoltaic performance of molecular donors.Compared with chlorinated molecule MDJ-Cl,the non-chlorinated analogue MDJ exhibits decreased miscibility with the non-fullerene acceptor Y6,can more efficiently quench the excitons of Y6.As a result,a improved PCE of 11.16% is obtained for MDJ:Y6 based SMOSCs.The results highlight the importance of fine-tuning the molecular structure to achieve high-performance SMOSCs.