The development of indoor photovoltaic devices for powering Internet of Things (IoT) sensors requires low-cost and sustainable components, making dye-sensitized solar cells (DSSCs) an ideal candidate for artificial light harvesting. The counter electrode plays a critical role in transferring electrons and catalyzing the reduction in the redox electrolyte. However, the traditional use of expensive and scarce platinum (Pt) limits the cost-effective, large-scale commercialization of these devices. While carbon-based materials offer a highly porous, conductive, and abundant alternative, commercial carbon pastes frequently require energy-intensive high-temperature sintering. In this study, we propose a sustainable, low-temperature, and screen-printable carbon composite counter electrode (LoT-HPC) using bio-derived hydroxypropyl cellulose (HPC) as a highly effective binder. Rheological characterizations confirm that the formulated LoT-HPC ink possesses an ideal shear-thinning profile and rapid structural recovery, ensuring excellent printability and film homogeneity. By comparing the custom LoT-HPC composite against a commercial high-temperature screen-printed graphite paste (HT-Elco) and a standard sputtered Pt-FTO electrode, we demonstrate the structural and electrocatalytic advantages of this material. When integrated into full DSSC devices and evaluated under low indoor illumination (1000 lux), the LoT-HPC cell delivers a power conversion efficiency (PCE) of 14.8% and a high short-circuit current density of 103.9 µA cm−2. Furthermore, the custom device demonstrated exceptional operational stability, retaining 98.6% of its initial efficiency (from 14.8% to 14.6%) after 200 h of continuous light-soaking and J-V cycling under 1000 lux. Ultimately, the successful implementation of the HPC binder enables the low-temperature fabrication of sustainable carbon counter electrodes without the need for energy-intensive thermal treatments, presenting a highly scalable pathway for indoor DSSC manufacturing.

ABSTRACT This work explores an innovative approach to convert CO 2 into a valuable energy resource using ionic liquid (IL)–based electrochemical systems. The employed ionic liquid, [DBUH][Im], combines the strong CO 2 affinity of imidazole with the high basicity of DBU, promoting selective carbamate formation while suppressing parasitic reactions. CO 2 chemisorption induces ion rearrangement at the electrode–electrolyte interface, generating a measurable open‐circuit voltage shift. However, the high viscosity of the pristine IL significantly restricts ionic mobility, especially after CO 2 absorption. Dilution with propylene carbonate improves conductivity and enhances electrochemical performance. A multiparametric study was conducted under realistic working conditions, evaluating gas flow rate influence, CO 2 /N 2 selectivity, operating temperature, and long‐term stability. Moreover, the introduction of a supporting‐salt further improved ionic conductivity, interfacial properties, and pore accessibility, leading to higher capacitance and harvested power. Overall, these results highlight the potential of tailored IL‐based electrolytes for integrated CO 2 capture and energy conversion technologies.

This work presents a novel technological solution based on molecular-template-assisted electrodeposition of nanostructured metallic palladium thin films on both the reference and counter-electrode of a MEMS-based EC-LPTEM cell. Nanostructuring dramatically increases the electroactive area, reducing RE potential oscillation and CE polarization, thus suppressing gas evolution. When galvanostatically loaded with hydrogen, nanostructured Pd forms a stable PdHα+β phase, functioning as a true on-chip reversible hydrogen electrode with excellent potential stability over extended timescales. While challenges such as Pd redeposition on the on-chip working electrode remains in particular circumstances, this method represents a major step toward accurate operando electrochemical studies and scalable on-chip reference electrode design for advanced microscale devices, enabling stable, reproducible electrochemistry and significantly improving the reliability of EC-LPTEM measurements.

ABSTRACT Polymers of Intrinsic Microporosity (PIMs) are a class of polymers characterized by a native microporous network resulting in a high surface area. PIMs also display a highly tunable and efficient gas permeability, attracting a lot of attention in several electrochemical applications. In this work. PIM‐1 was combined with a deep eutectic solvent (DES) for the production of a potentiometric sensor for CO2. This study reports the synthesis of both components, the fabrication of composite membranes via solvent casting and impregnation, and their evaluation as CO2 responsive materials together with a comprehensive characterization. The PIM‐1/DES materials demonstrated efficient CO2 capture and release behavior with open‐circuit voltage responses recorded under controlled CO2 exposure and adsorption–desorption cycling with full recovery. The membrane exhibited a response of 29 s in pure CO2 with a recovery time of 240 s. The sensors followed a logarithmic correlation between CO2 concentration and voltage variation and it showed a sensitivity of up to 9.6 mV/%CO2. These findings indicate that the developed sensor offers high reproducibility, fast response, and reliable detection of variable CO2 levels, underscoring its strong potential for practical implementation in environmental and industrial monitoring applications.

Here we report a comprehensive study of how liquid confinement determines the response of a cell designed to perform electrochemical liquid-phase transmission electron microscopy (EC-LPTEM). 2D and 3D simulations of chronoamperograms and voltammograms reveal how the geometry of the EC-LPTEM cell constrains mass transport to and from the working electrode, as well as the current distribution between the working and counter electrodes. STEM images of electrodeposited Pd are used to experimentally validate the simulations. The results clearly show how hindrance drives mass transport through different diffusion regimes over time and how the complex geometry constrains current distribution within the cell. The results presented here provide guidelines to i) help analyse the electrochemical measurements obtained in EC-LPTEM cells and ii) design future improved electrochemical cells for operando liquid phase TEM experiments.

In the last decades, the use of biochar has been receiving increasing attention for the development of electrochemical energy storage devices. In this work, the waste hazelnut shell biomass, a low cost and abundant agriculture residue within our territory, was valorized as feedstock for the synthesis of alkali-derived activated carbons, which were properly characterized and electrochemically tested, in the perspective of their use as new electrode material in energy storage applications. Two activated carbons have been identified as promising materials for this application and their electrochemical performances were further improved by including a doping step with copper (I) oxide, achieving the best specific capacitance of 123 F/g. Moreover, one of the two most promising activated carbons was tested in an EDLC symmetric device outperforming, at low power rates, reference materials in terms of specific energy density, reaching the value up to 40 Wh/kg, due to its remarkable specific capacitance of 55 F/g. In summary, this work proposes a sustainable and low energy demanding approach to transform waste biomasses into high value activated carbon materials for energy storage applications. The strategy not only promotes the reuse and valorization of hazelnut shell waste biomass, but it also supports a circular model with promising environmental and economic advantages.

Surface activation of transition metal chalcogenides (TMCs) is commonly attributed to electrochemical reduction and defect formation under applied bias. Herein, we demonstrate that for single-crystalline NiSeTe, a significant fraction of the surface transformation typically associated with electrochemical activation instead arises from purely chemical, sulfuric acid-driven (H2SO4) reconstruction occurring prior to any applied potential. Nearambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is employed to monitor the evolution of pristine, acid-exposed, and washed surfaces. Acid treatment selectively removes native TeOx species and Ni-O(H) environments, while heterogeneous sulfate-derived species collapse into a transient S(VI)-rich adlayer. Subsequent washing eliminates weakly bound sulfates and yields a chemically simplified, oxide-free NiSeTe surface with a thin, stable sulfate termination. Notably, operando, bias-controlled NAP-XPS measurements with simultaneous chronoamperometric current monitoring reveal that cathodic polarization under HER-relevant conditions does not further reduce the acid-reconstructed surface, indicating that sulfuric acid exposure already generates an oxide-free NiSeTe termination prior to electrochemical biasing. In contrast, anodic polarization under OER-relevant conditions promotes tellurium re-oxidation. These findings establish acid-driven chemical restructuring as a dominant contributor to surface activation in NiSeTe and underscore the importance of disentangling chemical and electrochemical effects in chalcogenide electrocatalysts.

Dye-sensitized solar cells (DSSCs) represent a promising technology for indoor energy harvesting owing to their high performance under low-intensity light and compatibility with low-cost coating and printing techniques. Carbon-based counter electrodes (CEs) offer an affordable Pt-free alternative for DSSCs, yet screen-printed carbon electrodes often contain organic binders such as ethyl cellulose (EC), which can hinder charge transport and electrolyte access to active sites. In this work, PVP-assisted sol–gel TiO 2 inorganic binders (SG) were investigated as alternatives to EC in carbon black/graphite (CB.G) inks for screen-printed CEs. The binders were synthesized from titanium isopropoxide (20 wt.%) in ethylene glycol with acetic acid (7 wt.%), while the PVP content was varied from 0.5 to 3 wt.% (SG0.5-SG3) to adjust the rheological behaviour and printability. All CB.G/SG inks exhibited flow behaviour suitable for screen-printing, and higher PVP content improved printed pattern definition, enabling a minimum resolved line width of 200 µm. After sintering at 480°C, Raman spectroscopy confirmed the anatase TiO 2 within the composite CEs, with crystallite sizes of 11–17 nm. Compared with the EC-based reference, the carbon/TiO 2 CEs exhibited improved mechanical stability, lower sheet resistance and more effective charge transfer at the interface between CE and I − /I 3 − electrolyte. Among the studied composite CEs, CB.G/SG2.5, prepared using a TiO 2 -based binder containing 2.5 wt. % PVP, showed the most favourable balance between adhesion to the FTO substrate, sheet resistance (149 Ω/sq) and charge-transfer resistance (20.01 Ω.cm 2 ). When implemented in DSSCs under LED indoor illumination, the CB.G/SG2.5 CE led to PCEs of 18.94% at 1000 lux and 15.41% at 200 lux, exceeding the corresponding Pt-based reference values of 18.11% and 14.34%, respectively. These results demonstrate the potential of PVP-stabilized TiO 2 inorganic binders as EC alternatives for screen-printed carbon-based CEs in indoor DSSCs.

In this work, we investigated the possibility of using a commercial tape entirely made of continuous carbon nanotubes (CNTs) for blue energy harvesting application. The tape was used to build the electrodes of a device harvesting energy from salinity gradient based on the capacitive mixing (CapMix) technique. The tape was used as it is or functionalized to enhance its storage properties and to obtain an asymmetric device. The electrodes underwent a full set of electrochemical characterizations to test the impact of the functionalization. Thanks to high electrical conductivity, remarkable specific capacitance and good chemical stability, the tape acted both as active material and current collector, eliminating the need for metallic current collectors, reducing the mass of the system and avoiding possible corrosion of the metals due to close contact with saline solutions. This approach provided a simple and easily scalable device able to produce electrical power from the mixing of two solutions at different salinities. The achieved power output stands at 75 mu W m(-2) in artificial seawater/freshwater and 1.2 mW m(-2) in artificial Mediterranean brine/seawater. These results contribute to the broader understanding of energy harvesting from salinity gradients, extending the technological application of CNT tape across the renewable energy field.

This work presents a method for copper electroplating carbon nanotube (CNT) yarns with a two-step electrodeposition process in copper baths. The proposed method uses a low viscosity organic electrolyte in the first step — copper acetate dissolved in acetonitrile to avoid hydrophobicity and cuprophobicity of the CNT. The method is scalable and resource-effective offering a promising approach for fabricating various types of CNT–metal composites for diverse applications. Flexible composite samples were fabricated using a two-step electrodeposition process on free-standing CNT-yarn wires. The intimate contact between copper and the CNTs was examined via scanning electron microscopy on focused ion beam cross-sections. X-ray diffraction analysis revealed that the deposited copper layer exhibited preferential crystal growth along the (111) orientation. X-ray photoelectron spectroscopy confirmed the predominance of metallic copper. The electrical resistivity of both the bare CNT-yarn and the electroplated Cu/CNT composite was accurately measured avoiding contact resistance stray effects, showing that the composite outperforms the bare CNT yarn by a factor of four. Furthermore, the Cu/CNT-yarn can be directly soldered to standard electrical connectors, making it a practical solution for integrating wire-like devices into textiles for Internet of Things.

This paper presents a proof-of-concept ultra-low voltage and ultra-low-power chronoamperometric sensing platform for non-enzymatic glucose detection, based on the co-design of a reconfigurable digital-based (DB) potentiostat and a mesoporous platinum (Pt) microelectrode. The DB potentiostat enables current readout and direct digitization from a 0.3V supply at nanowatt-level power, while the microelectrode geometry and mesoporous Pt nanostructuring provide non-enzymatic glucose sensitivity at physiologically relevant concentrations within an electrochemical operating window compatible with the voltage and power constraints of the readout. A frequency-domain signal and noise model of the DB potentiostat is derived for the first time and validated through simulations and measurements, providing a quantitative basis for the electrochemical/readout co-design. Fabricated in 130nm CMOS, the DB potentiostat achieves 5.6 pArms input-referred noise, corresponding to a 16.8 pA circuit level minimum detectable current, while consuming 1.65nW at VDD=0.3V. Electrochemical currents from 600 pA to 650 nA are experimentally measured with R2=0.991 linearity under ferrocyanide test conditions. Non-enzymatic glucose measurements with mesoporous Pt microelectrodes at physiologically relevant concentrations, under aerobic conditions and with ascorbic acid as an interferent, demonstrate, to the best of the authors’ knowledge, the lowest reported power consumption for CMOS non-enzymatic glucose readout, supporting the potential of the proposed platform for emerging point-of-care diagnostics applications.

Biomass offers a low-cost and sustainable carbon source. Yet, conventional pyrolytic routes remain energy intensive and require harsh processing conditions. Laser-induced carbonization provides a rapid, efficient and green alternative for the conversion of biomass into carbon structures. Building on the growing demand for sustainable alternatives to petroleum-derived polymers in laser writing, we investigate laser-induced carbon (LIC) produced from cellulose acetate (CA) membranes, a widely available biopolymer, via CO2 laser irradiation. The flame-retardant bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) enables localized carbonization, overcoming CA's poor thermal stability. By tuning laser parameters, namely the defocus distance and the number of passes, we selectively obtain amorphous carbon, activated carbon (AC), graphene oxide (GO), and laser-induced graphene (LIG). Among these, AC fabricated through a double-pass process at a defocus distance of 7.5 mm achieves outstanding electrochemical performance as a microsupercapacitor (μSC) electrode, delivering an areal capacitance of up to 63 mF cm-2, an energy density of 3.3 µWh cm-2, and a power density of 0.42 mW cm-2. These results outperform those of petroleum-based polymer-derived LIG while utilizing a potentially upcycled precursor. This work expands the scope of LIG precursors and offers a versatile platform for engineering sustainable carbon-based electrodes.

Exponential growth of interest in capacitive deionization (CDI) technology has been motivated by its low energy consumption and potential use in desalination and water softening. In this work, CDI was applied for water softening using a radial-flow cell designed according to the concept of a "percolation flow cell", combining flowthrough and flow-by configurations to achieve high efficiencies and electrosorption rates. To make this cell economically viable, the electrode was a commercial activated carbon felt (CF) with high specific surface area. The felt was chemically modified to create surface functional groups that could minimize the co-ion repulsion effect, while the use of asymmetric electrodes improved the electrosorption capacity. Considering the variation of mass transfer and residence time along the radial flow, two flow patterns were studied: (i) from the center of the electrode to the edge (CE), and (ii) from the edge to the center of the electrode (EC). For each configuration, evaluation was made of the effects of the applied current and flow rate, enabling determination of the influence of charge and mass transfer processes on the charging efficiency and the ion removal rates. The results indicated that modification of the CF using nitric acid to introduce negative oxygen groups on the surface was highly effective, with a 44.3 % improvement in capacitance, while the use of ethylenediamine led to only modest enhancement. The radial-flow cell showed a significant dependence on the flow direction. The EC flow provided a more uniform ionic flux convergence, which improved charge efficiency and ion transport, with optimal operation achieved at 1.25 A m- 2 and 22 mL min- 1. Under these conditions, combined with the EC flow direction, the system presented a salt adsorption capacity (SAC) of 25.04 mg g- 1 and specific energy consumption of 0.50 J mg- 1. The balance between performance and energy efficiency demonstrated the potential of this system for use in scalable water treatment applications.

The development of sustainable energy storage devices, such as supercapacitors (SCs), pushes towards innovative material science solutions. This study presents Hydroxypropyl Cellulose (HPC) as a promising fluorine-free binder (FFB) alternative to traditional fluorinated binders exploited in aqueous-based electrolytic systems. HPC offers water solubility and pH stability, making it an environmentally friendly option for aqueous electrolyte-based SCs. We investigated HPC's efficacy as a binder in activated carbon-based SC electrodes due to its salt out effect, comparing it with conventional Polyvinylidene Fluoride (PVDF) binder. Electrodes were tested in acidic (1 N H2SO4), neutral (1 N Na2SO4), and basic (1 N KOH) electrolytes, with titanium current collectors. Our findings reveal that HPC-based electrodes exhibit superior uniformity and interconnectivity, as evidenced by electron microscopy and surface area measurements. Electrochemical characterizations demonstrate that HPC electrodes outperform PVDF counterparts in all tested electrolytes, particularly in terms of chemical stability in basic solutions where PVDF degrades. The HPC devices achieved specific capacitances of 22.21 F g- 1 (acidic), 17.03 F g- 1 (neutral), and 23.86 F g- 1 (basic) with over 90 % retention after 10,000 charge-discharge cycles and 160 h of floating tests. These results suggest that HPC not only ensures environmental safety but also enhances performance and durability across various pH environments. In conclusion, HPC proved to be a sustainable and effective binder for electrochemical systems with both capacitive and faradic electrodes. Future research should focus on integrating HPC with more stable current collectors to further improve devices' performance, especially in acidic media, seawater and wastewater, thus advancing the field of eco-friendly energy storage technologies.

The rapid growth of the Internet of Things ecosystem has increased the need for sustainable, cost‐effective energy sources for indoor low‐power devices. Indoor photovoltaics offer a solution by harnessing ambient indoor lighting, with dye‐sensitized solar cells (DSSCs) emerging as strong candidates for these applications. When it comes to indoor environments, there is an increased demand for nontoxic and nonflammable solvents for electrolytes. The use of water‐based electrolytes is a promising way to address these issues, while ensuring the eco‐friendliness and sustainability of these devices. Herein, a DSSC system is employed featuring an aqueous gel electrolyte composed of xanthan gum, a biosourced polymer, and an iodide/triiodide redox couple. The performances of the cells are characterized under LED lighting, reaching efficiencies up to 3.5% in indoor conditions, and then integrated with an electric double‐layer capacitor, also based on a xanthan gum gel electrolyte, resulting in a fully aqueous device for indoor light‐energy harvesting and storage with an overall photoelectric conversion and storage efficiency of 1.45%.

A significant portion of the billions of Internet of Things (IoT) smart devices operate indoors, typically powered by batteries that require periodic recharging or disposal, raising sustainability concerns about maintenance and electronic waste production. This has generated increased interest in developing indoor photovoltaics (IPV) for self‐rechargeable IoT devices. Among IPV technologies, dye‐sensitized solar cells (DSSCs) offer high conversion efficiency, stability, and scalability. However, the use of toxic and flammable solvents, such as acetonitrile (ACN) and 3‐methoxypropionitrile (MPN), remains a concern. This research investigates γ‐valerolactone (γ‐VL), a sustainable, low‐toxic solvent derived from cellulosic biomass, as an alternative for DSSC electrolytes. Electrolytes based on I − /I 3 − redox shuttle are prepared with γ‐VL, MPN, and ACN and studied in both dummy cell and full device configuration. Results show that γ‐VL is unsuitable for outdoor DSSCs due to slower ion diffusion and reduced I 3 − reduction at the counter electrode. However, γ‐VL DSSCs outperform those using ACN and MPN under indoor light, demonstrating equivalent short‐circuit currents but higher open‐circuit voltages, improved fill factors, and enhanced overall efficiency, enabled by lower recombination at the photoanode. These findings position γ‐VL as a promising, eco‐friendly option for DSSC electrolytes in indoor IoT applications.

With the rising levels of atmospheric CO2, electrochemistry shows great promise in decarbonizing industrial processes by converting CO2 into valuable products through scalable and sustainable technologies. In this framework, the present study investigates the solar-driven CO2 reduction toward carbon monoxide, achieved by the integration between the electrochemical reactor and dye-sensitized solar cells (DSSCs), both in experimental and modeling perspectives. COMSOL® Multiphysics 6.3 was used to develop a detailed finite element method model of the electrochemical cell integrated with a photovoltaic module, validated with the experimental results that demonstrated a strong correlation. A 2D model was designed, incorporating cathode and anode regions divided by an ion-exchange membrane. The model includes platinum foil and silver nanoparticles as catalysts for the oxygen evolution reaction and CO2 reduction reaction, respectively. Integration with the fundamental equations of the DSSCs was simulated to analyze the solar-driven CO2 reduction behavior under solar irradiance variations, offering a valuable tool for optimizing operating conditions and predicting the device performance under different environmental conditions. The integrated device successfully produces CO with a faradaic efficiency of 73.85% at a current density of J = 3.35 mA/cm2 under 1 sun illumination, with the result validated and reproduced by the mathematical model. Under reduced illumination conditions of 0.8 and 0.6 suns, faradaic efficiencies of 68.5% and 64.1% were achieved, respectively.

When two solutions with different compositions are mixed, the free mixing energy is released. This principle is exploited in salinity gradient power technologies like capacitive mixing (CapMix), where mixing occurs in a supercapacitor. Since this energy release holds true also for gases, research moves in the direction of harvesting energy from anthropic CO2. To do so, it is proposed for the first time to exploit an ionic liquid (IL), both as an electrolyte and CO2 absorbing medium in a CapMix cell. The mechanism consists in flowing a CO2‐rich gas stream, alternated to a N2 stream, during the charging/discharging of two electrodes. The CO2 strongly affects the electrode/IL interface and the IL physicochemical properties thereby converting the released mixing energy into electrical energy. Unlike water‐based systems, where energy harvesting relies on electric double‐layer expansion, we propose a new mechanism based on electrochemical potential variations during CO2 capture/release, supported by molecular dynamics modeling. Key results include maximum voltage rise of 40 mV and energy and power densities of 40 μWh m−2 and 0.8 mW m−2. These findings clarify the mechanism behind the electrochemical phenomena occurring when CO2 interacts with IL and open the way to a new generation of electrochemical systems to harvest energy from CO2 emission.