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Electrochemical valorization of biomass is a potential route for the interfacial synthesis of products with high added value; however, its thermodynamically unfavorable nature demands substantial electrical driving force for achieving the desired rate. We illustrate a fundamentally unique approach for electrochemical valorization in an electrochemical neutralization fuel cell (ENFC) where oxidative valorization of biomass to value-added products and reductive hydrogen fuel synthesis are spontaneously paired during electric power production. We further show that the selectivity of the valorization pathway can be controlled through the interfacial electrochemistry of the catalytic anode/electrolyte interface. The capability of the ENFC to synthesize value-added products and clean molecular fuels during electric power production by harvesting the energy of neutralization will enrich the chemistry of energy conversion with immense techno-commercial implications.

TiB2is extensively explored due to its outstanding properties, for example, high electrical conductivity, high thermal conductivity, chemical stability, high hardness, low density, and solidity. Herein, we developed a novel nanocomposite structure (NCS) featuring exfoliated TiB2decorated with Ru nanoparticles, denoted as exfoliated TiB2@Ru. This novel electrode material was synthesized using an ultrasound-assisted method. Both the pristine TiB2and exfoliated TiB2@Ru NCS were characterized by FTIR, XRD, FE-SEM, EDX, AFM, and XPS analyses. Furthermore, the electrochemical characteristics of all TiB2electrodes were measured by CV, GCD, and EIS to evaluate their application to supercapacitors. The exfoliated TiB2@Ru NCS exhibited an enhanced specific capacitance of 744 F/g compared with exfoliated TiB2(464 F/g) and pristine TiB2(296 F/g) at a current density of 1 A/g in 3 M KOH electrolyte solution using a three-electrode system. The as-prepared exfoliated TiB2@Ru solid-state supercapacitor delivered a significantly higher capacity retention of 97 % than the pristine TiB2(92 %), even after 5000 cycles. Therefore, the interconnected sheet-like exfoliated TiB2@Ru NCS electrode offers excellent capacitive performance for energy storage applications. As a result, the design and/or suitability for improving highly active electrochemical sites in exfoliated TiB2through the incorporation of Ru nanoparticles by ultrasonic method showed excellent charge storage performance.

Here we show a strategy to expand the working voltage of aqueous metal batteries beyond the thermodynamic limit of 1.23 V by modifying the interfacial chemistry existing at the cathode/electrolyte interface. Highly nonwettable carbon nanoparticle cathode/electrolyte interface with a freely diffusing electron acceptor kinetically muted water decomposition due to reduced contact between water and the electrode, expanding the working voltage far beyond 1.23 V. Zn battery equipped with hydrophobic carbon nanoparticle cathode delivered an open-circuit voltage (OCV) of 2.6 V with capacity (∼930 mAh/g), energy (∼2420 Wh/kg @ 50 mA/cm2), and power densities (∼83 W/kg) remarkably higher than conventional Pt-based aqueous Zn-air batteries (OCV = 1.5 V, ∼650 mAh/g, ∼1161 Wh/kg, and ∼43 W/kg). When probed with in situ and ex situ FTIR spectroelectrochemistry and galvanostatic intermittent titration technique, wettable carbon particles (contact angle = ∼20°) are found to catalyze parasitic oxygen evolution reaction, while their nonwettable counterpart (contact angle = ∼117°) dominantly catalyzed electron acceptor’s redox reaction by inhibiting any such parasitic chemistry. Zn batteries equipped with carbon cathode contribute to a Pt-free battery having a closed cathode, addressing the complexity of carbonate clogging and electrolyte evaporation often encountered in open-air batteries, and could be used to power electrical appliances.

Polyaniline (PANI) nanostructures were synthesized via an acid-free green route using redox-active, water-soluble 9,10-Anthraquinone-2-sulfonic acid sodium salt (AQSA). As a counter anion for the PANI backbone, the AQSA plays an important role in polyaniline (PANI) chain growth and as a morphology regulator. The AQSA doped PANI shows pronounced specific capacitance with effective cycling stability. As-synthesized nanotubular structures of PANI_AQSA (0.5, 1.0, and 1.5) with various concentration ratios of aniline to AQSA were achieved in appreciable yield. The intrinsic physico-chemical properties were analyzed using various physico-analytical techniques such as Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), powder X-ray diffraction analysis (XRD), Fourier Transmission Infrared spectroscopy (FT-IR), X-ray Photo Electron Spectroscopy (XPS), and Raman analysis. Nanotubular structures of PANI_AQSA were analyzed using FESEM studies. The electrochemical studies, galvanostatic charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS) were methodically investigated. PANI_AQSA_1.5 portrays enhanced specific capacitance of 440 Fg−1at 1 Ag−1(three-electrode system) in 1 M sulphuric acid electrolyte than its regular Cl−counter ion (276 Fg−1at 1 Ag−1). The fabricated symmetric PANI_AQSA//PVA_H2SO4//PANI_AQSA supercapacitor showed a specific capacitance of 391 Fg−1at 1 Ag−1with 93 % capacitance retention for ~1000 cycles.

Here we report an ON–OFF effect on electrocatalytic amplification when the molecules are connected to each other on an electrode surface. When the molecular connection is achieved, the redox potential of the catalytic redox entity is significantly upshifted with concurrent experience of a more electron-withdrawing atmosphere, and the electron transfer to and from the catalytic center is accelerated, rendering the molecules with strong electroreducing character; however, the overall outcome is dictated by the surface charge. Outer sphere redox probes and X-ray photoelectron spectroscopy evidently revealed that a positive surface charge is preserved in acidic and neutral media after molecular connection which is in parallel with the corresponding electrocatalytic amplifications toward oxygen reduction reaction (ORR), suggesting the electrodics after molecular connection is extremely pH dependent. Surface charge present after molecular connection is significantly neutralized by the abundant hydroxyl groups in alkaline media, making the central metal ion’s atmosphere less electron deficient and downshifting its redox potential (compared to the case in acidic and neutral media), thereby reducing the disparity in electroactivity before and after molecular connection. This study underlines that after molecular connection surface charge is the key as it can turn on and turn off the redox entity responsible for electrochemical amplifications. The solvent dependence and redox potential upshift outlined here for monolayer electrodes are nullified during bulk polymerization, indicating the circumstances leading to molecular connection are different from bulk polymerization. Since the surface charge can be modulated by connecting the molecules and tuning the surrounding media, the proposed strategy brings forward a way to tune the interfacial activity and is expected to have implications in electrocatalysis, selective sensing, ion screening, and so on.

Here we show a surrogate strategy for power production, wherein light is used to actuate a discharge chemistry in the cathode of an aqueous rechargeable battery (ARB). The proposed photo battery consists of a titanium nitride photoanode, promising cathode material iron(III) hexacyanoferrate(II) as the battery active species and Na2S2O8as the chemical charging agent. The photo battery delivered negligible capacity in the dark and the capacity shot up to 77.8 mAh/g when artificially shined light, confirming that the battery chemistry is light driven. In the ambient light, the device retained 72% of its artificial light discharge capacity with a stable cycling for more than 100 cycles. Further, an unprecedented means for charging the battery rapidly is presented using Na2S2O8and it revitalized the battery in 30 s without any external bias. This methodology of expending a photoanode extends to a battery that is free from dissolution of active materials, irreversible structural changes, spontaneous deinsertion reactions, and safety concerns commonly encountered in the state of the art anode materials in ARBs. Apart from bringing out a sustainable way for power production, this device opens up avenues for charging the battery in the likely events of electrical input unavailability, while solving the critcial issues of longer charging time and higher charging voltage.