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MgHPO 4 has been introduced as a reactant that interacts with LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) to achieve the dual modification of Mg 2+ gradient doping and Li 3 PO 4 surface coating. The structure, morphology, elemental distribution, and electrochemical properties of the materials are elaborately explored using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. On the one hand, Mg 2+ gradient doping stabilizes the crystal structure of the Li + /Ni 2+ cation and minimizes its disorder. On the other hand, the coating of the fast lithium-ion conductor Li 3 PO 4 not only increases the rate of lithium-ion diffusion at the electrode–electrolyte interface but also protects the cathodic material and mitigates electrolyte corrosion. The dual-modified NCM622 cathode exhibits remarkable cycling performance, retaining 89.57% of its capacity after 200 cycles at 1C from 2.8 to 4.3 V and 79.03% after 100 cycles at 3C from 2.8 to 4.5 V. Additionally, the dual-modified cathode exhibits better electrode kinetics and a reversible capacity of 119.4 mA h g ?1 at 10C. This straightforward dual modification technique improves the lithium-ion diffusion kinetics at the interface while also stabilizing the internal crystal structure of Ni-rich cathode materials.

The use of methanol (MeOH) in direct methanol fuel cells has increased the interest in the search for new electrode materials and catalysts that allow the oxidation of MeOH to be carried out under conditions that satisfy their practical applications: low cost, stability, and high catalytic activity. In this work, electrochemical and quantum chemical methods were used to study peculiarities of the electrocatalytic system 2,5-di-Me-pyrazine-di- N -oxide–methanol at single-walled and multi-walled carbon nanotube (CNT) paper electrodes in comparison with a glassy carbon (GC) electrode in 0.1 M Bu 4 NClO 4 solution in acetonitrile (MeCN). The adsorption energies of MeOH, CH 3 COOH and H 2 O on the CNT surface were determined by quantum chemical modeling; this opened the door for the explanation of effects found in the Pyr 1 –MeOH catalytic system and for the ascertainment of factors affecting the catalytic efficiency of the process at CNT electrodes. We believe that this research will be helpful in using this process in electrocatalysis, sensors and direct methanol fuel cells, since the deactivation of aromatic di- N -oxides (as opposed to processes involving noble metals or noble metal oxides) is insignificant.

The unwavering focus on renewable energy generation has opened a wider research scope towards the study of electrocatalytic water splitting. In this regard, the present work deals with a low-cost synthesis strategy enabling large scale production of vanadium pentoxide (V2O5) electrocatalysts for the oxygen evolution reaction (OER). Polycrystalline V2O5 nanostructures with a 2D flat nanorod-like morphology with a rod length of about 1 μm were developed using a polymer-assisted solution technique. Benefitting from their unique morphology, V2O5 nanorods showed commendable OER properties with a low Tafel slope value of 88 mV dec?1 and overpotential (ηOER) of 310 mV at 10 mA cm?2. With a stable catalytic performance for 12 h, the V2O5 nanorods grown with polymer assistance is proposed as a promising candidate for OER activity in the present study.

Silicon (Si) is an important anode material for lithium ion batteries (LIBs), and increasing the loading of Si electrodes is an important step towards commercialization. However, half cells commonly used for Si studies are limited by polarization of the lithium (Li) counter electrode, especially at high Si loading. To study the interplay between Si and Li electrodes, a set of electrochemical impedance spectroscopy (EIS) spectra are generated using cycled Si half cells at four different potentials in the charge–discharge profile, and then repeated using symmetric Si/Si and Li/Li cells assembled from half cells cycled to equivalent stages in the cycle. Distribution of relaxation times (DRT) analysis is used to design equivalent circuits (ECs) for both Si/Si and Li/Li symmetric cells incorporating both electrolyte and electrode-related diffusion, and these are applied to the half cells. The results demonstrate that the behaviour of half cells is dominated by the solid electrolyte interphase (SEI) impedances at the Li counter electrode at the low and high potentials where the Li+ mobility signal in Si is limited, while the Si electrode is dominant at intermediate potentials where the signal from mobile Li+ is strong. EIS studies of Si half cells should therefore be performed at intermediate potentials, or as symmetric cells.

Despite the remarkable strides made in perovskite solar cell (PSC) research, the incorporation of doped hole transport materials (HTMs) presents a commercialization bottleneck. This study presents a chlorine-substituted polythiophene-based, dioxobenzodithiophene-containing conjugated polymer (P2T-Cl) as a promising dopant-free HTM. The highest occupied molecular orbital of P2T-Cl aligns well with PSCs, and flash-photolysis time-resolved microwave conductivity (TRMC) measurements reveal a high hole transfer yield of 0.99 for P2T-Cl compared to the non-chlorinated analogue of P2T (0.97) and non-doped polytriarylamine (PTAA) (0.79). Consequently, P2T-Cl exhibits a higher power conversion efficiency (PCE) without dopants (15.40%) compared to P2T (15.18%) and the standard polymer HTM PTAA (12.74%). This work presents a compelling example of a dopant-free polymer HTM with a simple structure for PSCs.

Post synthetically-modified UiO-66-NH2 with a molecular cobaloxime [Co(DMG)2Cl2] (DMG = dimethylglyoxime) catalyst displays excellent photo-(404 μmol g?1 h?1) and electrocatalytic H2 evolution activity in an aqueous solution. Several analytical and spectroscopic methods, including femtosecond transient absorption spectroscopy and DFT, revealed the unique interaction between cobaloxime and the MOF leading to enhanced catalytic activity.

This study investigates the modification of materials by doping with foreign elements to enhance electrocatalytic activity and focuses on the engineering of an inorganic material composed of transition heterometal-rich pentlandite (Fe3Co3Ni3S8, FCNS) doped with silicon (FCNSSi) as a bifunctional catalyst for the overall electrochemical water splitting process. The FCNSSi electrode exhibits remarkable catalytic activity for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The OER performance of FCNSSi was evaluated in a 1.0 M KOH solution, achieving an overpotential of 313 mV at 10 mA cm?2. The FCNSSi electrode exhibits a current density of ?10 mA cm?2 at a remarkably low overpotential of 164 mV with a Tafel slope of 80.7 mV dec?1 in HER. Density functional theory (DFT) calculation suggests that Si doping adjusts the binding energies of intermediates on the surface, which weakened the *OH, *O, and *OOH adsorption energies, resulting in enhanced activity for both OER and HER. Moreover, Si doping enhances the hydrogen adsorption activity of all sites. Finally, a two-electrode zero-gap cell assembly was used to investigate the durability of FCNSSi catalyst towards efficient and durable alkaline water electrolysis, demonstrating the promising potential of this catalyst for practical applications at 500 mA cm?2.

The efficiency of organic solar cells has increased significantly in the recent years due to the continued improvement in material properties, including the charge carrier mobilities within the bulk heterojunction. However, common strategies to measure the mobility of electrons and holes, such as the space-charge-limited-current approach, rely on purpose-made single carrier diodes, which are operated in the injection regime. Alternatively, impedance spectroscopy measurements can yield an effective mobility as well as a photoconductance mobility for solar cells under realistic operating conditions. There exist various theoretical interpretations that relate the experimentally determined values of the effective mobility with the mobility of the individual charge carriers (i.e. electrons and holes). Furthermore, the relationship between the effective and photoconductance mobility has not been clarified yet. This study shows how the effective and photoconductance mobilities can be combined in a system of equations to calculate the individual mobilities of the faster and slower carriers. Finally, these considerations are applied to determine individual carrier mobilities in several blend systems, including fullerene-based P3HT:PC60BM solar cells, as well as non-fullerene devices based on PM6:Y11-N4, PM6:Y5, PPDT2FBT:Y6, PM6:Y11, PM6:N4, and PM6:Y6. These results were validated with mobility values obtained via the space-charge-limited-current approach.

Replacing water oxidation by the thermodynamically more favorable glycerol oxidation reaction in a photoelectrochemical (PEC) cell is highly desirable, which can not only improve the energy efficiency of hydrogen evolution, but also produce value-added chemicals, given that glycerol is easily accessible as a major byproduct from the biodiesel industry. Herein, a BiVO4/CoV-LDHs/Ag photoanode has been fabricated via a simple electrodeposition and redox strategy, which exhibits excellent PEC activity toward glycerol oxidation. A high photocurrent density of 7.15 mA cm?2 can be achieved at 1.23 V vs. reversible hydrogen electrode, in 0.5 M Na2SO4 solution with 0.1 M glycerol under AM 1.5G illumination, which is 2.7 times that of the pristine BiVO4 photoanode. The significantly enhanced PEC performance can be attributed to the narrowed optical band gap, and improved charge separation and injection efficiencies after surface deposition of CoV-LDHs/Ag on the BiVO4 photoanode. As a result, greatly improved hydrogen production efficiency has been achieved by coupling the photo-electrochemical glycerol oxidation on the BiVO4/CoV-LDHs/Ag photoanode, with the evolved hydrogen gas (123.5 mmol m?2 h?1) nearly double that when using the pristine BiVO4 photoanode.

Recently, aqueous-based redox flow batteries with the manganese (Mn2+/Mn3+) redox couple have gained significant attention due to their eco-friendliness, cost-effectiveness, non-toxicity, and abundance, providing an efficient energy storage solution for sustainable grid applications. However, the construction of manganese-based redox flow batteries remains difficult due to severe intrinsic issues, including poor cyclability and limited capacity. During the past few decades, several scientific attempts have been made to alleviate the issues fundamentally enabling a pathway for high performance redox flow batteries. Herein, various developments of manganese-based redox flow batteries are methodically understood and reviewed. Moreover, the charge storage chemical reaction mechanism of manganese redox couples under various conditions is conferred providing an excellent opportunity to design scalable, affordable and environmentally benevolent manganese-based redox flow batteries for futuristic grid applications. The remaining challenges are tabulated and the authors’ perspectives are highlighted for the highly promising manganese redox couple.