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Improving the perovskite/electron-transporting layer (ETL) interface is a crucial task to boost the performance of perovskite solar cells (PSCs). This is utterly fundamental in an inverted (p–i–n) configuration using fullerene-based ETLs. Here, we propose a scalable strategy to improve fullerene-based ETLs by incorporating high-quality few-layer graphene flakes (GFs), industrially produced through wet-jet milling exfoliation of graphite, into phenyl-C61-butyric acid methyl ester (PCBM). Our new composite ETL (GF:PCBM) can be processed into an ultrathin (∼10 nm), pinhole-free film atop the perovskite. We find that the presence of GFs in the PCBM matrix reduces defect-mediated recombination, while creating preferential paths for the extraction of electrons towards the current collector. The use of our GF-based composite ETL resulted in a significant enhancement in the open circuit voltage and fill factor of triple cation-based inverted PSCs, boosting the power conversion efficiency from ∼19% up to 20.8% upon the incorporation of GFs into the ETL. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs), including the most established electrochemical double layer capacitors (EDLCs), are energy storage systems that can be charged in the second timescale, while sustaining a great number of re-charge cycles without losing efficiency. Undoubtedly, their major drawback is their insufficient energy density compared to batteries. Meanwhile, the reduction of the SC costs using cheap and sustainable electrolytes is also a trivial criterion to be considered in the competition race of the energy storage technologies. In this work, we report an extended characterization of aqueous SCs, screening acidic, neutral and alkaline electrolytes, as well as the addition of KI as a prototypical redox additive, and performing both two- and three-electrode configuration measurements. By using near-neutral electrolytes, our aqueous EDLCs can reach a maximum cell voltage superior to 2 V, enabling energy densities higher than 18 W h kg−1 (comparable or approaching those of lead acid and Ni–Cd batteries) at a power density up to almost 7 kW kg−1 (significantly superior to those of competing battery technologies). The introduction of redox additives can significantly increase the capacity of the SCs. However, compared to EDLCs, both the cell voltage and the energy efficiency of the SCs decrease because of partially irreversible faradaic redox reactions and overpotentials of kinetically limited redox reactions. While debunking the myth that aqueous SCs exhibit low energy density, our study also remarks the importance of adequately assessing aqueous SCs, showing the current challenges of advanced SC architectures alternative to EDLCs. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of an active material for supercapacitors (SCs), namely α-Fe2O3/carbon composite (C-Fe2O3) made of elongated nanoparticles linearly connected into a worm-like morphology, by means of electrospinning followed by a calcination/carbonization process. The resulting active material powder can be directly processed in the form of slurry to produce SC electrodes with mass loadings higher than 1 mg cm−2 on practical flat current collectors, avoiding the need for bulky porous substrate, as often reported in the literature. In aqueous electrolyte (6 M KOH), the so-produced C-Fe2O3 electrodes display capacity as high as ~140 mAh g−1 at a scan rate of 2 mV s−1, while showing an optimal rate capability (capacity of 32.4 mAh g−1 at a scan rate of 400 mV s−1). Thanks to their poor catalytic activity towards water splitting reactions, the electrode can operate in a wide potential range (−1.6 V–0.3 V vs. Hg/HgO), enabling the realization of performant quasi-symmetric SCs based on electrodes with the same chemical composition (but different active material mass loadings), achieving energy density approaching 10 Wh kg−1 in aqueous electrolytes. [ABSTRACT FROM AUTHOR]

The development of hydrogen storage and conversion technologies, such as electrolyzers and fuel cells, significantly benefits from the electrochemical deposition of platinum (Pt). This process is also crucial for creating coatings for internal combustion engines and electronic devices. Conventionally, Pt electrochemical deposition occurs in acidic media, which efficiently dissolves Pt salts but necessitates the use of expensive, corrosion-resistant substrates like noble metals and other critical raw materials such as titanium (Ti). This research explores the alkaline electrochemical deposition of Pt, aiming to overcome the limitations associated with acidic media. The study begins with developing strategies to dissolve commonly used Pt precursors from acidic baths into stable complexes suitable for alkaline environments. Various protocols, including chronoamperometric and potentiometric ones, are employed to evaluate the Pt electrodeposition on substrates such as nickel (Ni) foams and stainless steel meshes, which are relevant to alkaline water electrolysis. Optimization of the electrochemical deposition parameters is carried out to enhance the hydrogen evolution reaction (HER) activity of the resulting electrodes. The most HER-active electrodes are then tested as cathodes in alkaline electrolyzers (AELs), demonstrating superior performance compared to commercially available platinized Ti felts. These advanced AELs can operate at high current densities (≥1 A cm⁻2) at cell voltages below 2 V, thereby rivaling state-of-the-art acidic water electrolysis systems. Looking forward, the alkaline electrodeposition of Pt presents a sustainable approach to the usage of Pt in green hydrogen production. Pt recovered from operating or end-of-life electrolyzers and fuel cells can be reused to restore or enhance the catalytic activity of cathodes in alkaline water electrolysis, ensuring efficient and eco-friendly Pt utilization. [Display omitted] • Alkaline electrochemical deposition of Pt explored on various substrates used in AELs and AEM-ELs. • Pt precursors can form stable complexes in 1 M and 6.9 M KOH at 70 °C. • Fine-tuned Pt films achieve overpotential as low as 0.067 V at −100 mA cm⁻2. • Electrochemically deposited Pt films were validated in high-performance AEL cells. • In-situ electrochemical Pt deposition can be used for upgrading/healing AEL and AEM-EL cathodes. [ABSTRACT FROM AUTHOR]

Improving the perovskite/electron-transporting layer (ETL) interface is a crucial task to boost the performance of perovskite solar cells (PSCs). This is utterly fundamental in an inverted (p-i-n) configuration using fullerene-based ETLs. Here, we propose a scalable strategy to improve fullerene-based ETLs by incorporating high-quality few-layer graphene flakes (GFs), industrially produced through wet-jet milling exfoliation of graphite, into phenyl-C61-butyric acid methyl ester (PCBM). Our new composite ETL (GF:PCBM) can be processed into an ultrathin (∼10 nm), pinhole-free film atop the perovskite. We find that the presence of GFs in the PCBM matrix reduces defect-mediated recombination, while creating preferential paths for the extraction of electrons towards the current collector. The use of our GF-based composite ETL resulted in a significant enhancement in the open circuit voltage and fill factor of triple cation-based inverted PSCs, boosting the power conversion efficiency from ∼19% up to 20.8% upon the incorporation of GFs into the ETL., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)