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In the quest for more efficient and cost-effective electrocatalytic systems, careful selection of catalysts and substrates plays a pivotal role. This study introduces an approach by synthesizing and depositing NiFe-layered double hydroxide (NiFe-LDH) catalysts on commercial AISI 304 substrates by using a low-temperature spray-coating technique. Through systematic investigations, the influence of processing conditions, such as the synthesis, ultrasonic power for having a stable nanoparticle’s dispersion, and spray cycle optimization on the electrochemical and morphological properties of the coatings, is thoroughly explored. The results showcase exceptional catalytic performance, achieving an overpotential of 230 mV at 10 mA/cm2, with enhanced stability even at high current densities of 500 mA/cm2. The study highlights the significance of meticulous processing optimization and presents a scalable methodology that holds great potential for developing catalysts for oxygen evolution reactions (OER) and facilitates their integration into industrial processes.

It was found that high methylamine amounts allow the 3D stabilization of mixed cation perovskites in correlation with the molecular interaction of the MA molecules inside the precursor, leading a pathway for antisolvent free deposition method for mixed cation perovskites using methylamine route.

Within the most mesmerizing materials in the world of optoelectronics, mixed halide perovskites (MHPs) have been distinguished because of the tunability of their optoelectronic properties, balancing both the light-harvesting efficiency and the charge extraction into highly efficient solar devices. This feature has drawn the attention of analogous hot topics as photocatalysis for carrying out more efficiently the degradation of organic compounds. However, the photo-oxidation ability of perovskite depends not only on its excellent light-harvesting properties but also on the surface chemical environment provided during its synthesis. Accordingly, we studied the role of surface chemical states of MHP-based nanocrystals (NCs) synthesized by hot-injection (H-I) and anion-exchange (A-E) approaches on their photocatalytic (PC) activity for the oxidation of β-naphthol as a model system. We concluded that iodide vacancies are the main surface chemical states that facilitate the formation of superoxide ions, O2●–, which are responsible for the PC activity in A-E-MHP. Conversely, the PC performance of H-I-MHP is related to the appropriate balance between band gap and a highly oxidizing valence band. This work offers new insights on the surface properties of MHP related to their catalytic activity in photochemical applications.

While perovskite solar cells (PSCs) have been developed with different device architectures, mesoporous devices have provided the highest power conversion efficiencies. In this work, the working mechanism of both positive-intrinsic-negative (p-i-n) and negative-intrinsic-positive (n-i-p) meso-superstructured (MSSC) PSCs, which include a thin interlayer of porous alumina at the bottom electrode, is explored. Interestingly, for both p-i-n and n-i-p architecture, the mesoporous configuration was more efficient than its planar counterpart. For MSSC SnO2-based n-i-p devices, that result was primarily due to an increase in Vocand Jsc, resulting from improved band alignment and filling of the electron trap states (n-doping at the SnO2/perovskite interface), which led to devices with 21.0% efficiency and 20.3% stabilized power output (SPO). Although MSSC NiOx-based p-i-n meso-superstructured devices were less efficient due to lower Voc, a slightly higher Jscand fill factor improvement was achieved by the Al2O3mesoporous layer, resulting in devices with 16.9% efficiency. Importantly, the electronic nature of the perovskite is dependent upon its physical confinement within a mesoporous scaffold. Therefore, either p- or n-type semiconductor/perovskite interfaces can be engineered by selectively modifying the semiconductor behavior with the introduction of an insulating mesoporous scaffold interlayer.

Organic–inorganic hybrid perovskite materials have recently been investigated in a variety of applications, including solar cells, light emitting devices (LEDs), and lasers because of their impressive semiconductor properties. Nevertheless, the perovskite structure has the ability to host extrinsic elements, making its application in the battery field possible. During the present study, we fabricated and investigated the electrochemical properties of three-dimensional (3D) methylammonium lead mixed-halide CH3NH3PbI3-xBrxand two-dimensional (2D) propylammonium-methlylammonium lead bromide (CH3NH3)2(CH3(CH2)2NH3)2Pb3Br10hybrid perovskite thin films as electrode materials for Li-ion batteries. These electrodes were obtained by solution processing at 100 °C. CH3NH3PbBr3achieved high discharge/charge capacities of ∼500 mA h g–1/160 mA h g–1that could account also for other processes taking place during the Li intercalation. It was also found that bromine plays an important role for lithium intercalation, while the new 2D (CH3NH3)2(CH3(CH2)2NH3)2Pb3Br10with a layered structure allowed reversibility of the lithium insertion–extraction of 100% with capacities of ∼375 mA h g–1in the form of a thin film. Results suggest that tuning the composition of these materials can be used to improve intercalation capacities, while modification from 3D to 2D layered structures contributes to improving lithium extraction. The mechanism of the lithium insertion–extraction may consist of an intercalation mechanism in the hybrid material accompanying the alloying–dealloying process of the LixPb intermetallic compounds. This work contributes to revealing the relevance of both composition and structure of potential hybrid perovskite materials as future thin film electrode materials with high capacity and compositional versatility.

Optimization of the interface between the electron transport layer (ETL) and the hybrid perovskite is crucial to achieve high-performance perovskite solar cell (PSC) devices. Fullerene-based compounds have attracted attention as modifiers on the surface properties of TiO2, the archetypal ETL in regular n-i-p PSCs. However, the partial solubility of fullerenes in the aprotic solvents used for perovskite deposition hinders its application to low-temperature solution-processed PSCs. In this work, we introduce a new method for fullerene modification of TiO2layers derived from nanoparticles (NPs) inks. Atomic force microscopy characterization reveals that the resulting ETL is a network of TiO2-NPs interconnected by fullerenes. Interestingly, this surface modification enhances the bottom interface of the perovskite by improving the charge transfer as well as the top perovskite interface by reducing surface trap states enhancing the contact with the p-type buffer layer. As a result, rigid PSCs reached a 17.2% power conversion efficiency (PCE), while flexible PSCs exhibited a remarkable stabilized PCE of 12.2% demonstrating the potential application of this approach for further scale-up of PSC devices.

An investigation on the cooling-induced crystallization in three thermoplastic polyurethanes based on MDI, PTMG, and 1.4-BD as chain extender with different hard segment content is reported. Thermal transitions were determined using differential scanning calorimetry (DSC) measurements at different cooling rates, and thermal stability was studied by thermogravimetric analysis. Changes in Raman spectra were useful to correlate the thermal transitions with changes in the morphology of the polymers. The dissimilarity in the composition gave different rheological behavior in the molten state, indicated by the temperature dependence of the viscosity. The mechanical properties and the crystallinity was influenced not only by the cooling rate but also by the hard segment content. Thermoplastic polyurethanes with more hard segment content formed more crystalline hard domains as evidenced by the DSC and atomic force microscopy results.

Fabrication of solution-processed perovskite solar cells (PSCs) requires the deposition of high quality films from precursor inks. Frequently, buffer layers of PSCs are formed from dispersions of metal oxide nanoparticles (NPs). Therefore, the development of trustable methods for the preparation of stable colloidal NPs dispersions is crucial. In this work, a novel approach to form very compact semiconducting buffer layers with suitable optoelectronic properties is presented through a self-functionalization process of the nanocrystalline particles by their own amorphous phase and without adding any other inorganic or organic functionalization component or surfactant. Such interconnecting amorphous phase composed by residual nitrate, hydroxide, and sodium ions, proved to be fundamental to reach stable colloidal dispersions and contribute to assemble the separate crystalline nickel oxide NPs in the final film, resulting in a very homogeneous and compact layer. A proposed mechanism behind the great stabilization of the nanoparticles is exposed. At the end, the self-functionalized nickel oxide layer exhibited high optoelectronic properties enabling perovskite p-i-n solar cells as efficient as 16.6% demonstrating the pertinence of the presented strategy to obtain high quality buffer layers processed in solution at room temperature.

Since the first reports of efficient organic–inorganic perovskite solar cells in 2012, an explosion of research activity has emerged around the world, which has led to a rise in the power conversion efficiencies (PCEs) to over 20%. Despite the impressive efficiency, a key area of the device which remains suboptimal is the electron extraction layer and its interface with the photoactive perovskite. Here, we implement an electron collection “bilayer” composed of a thin layer of zirconia coated with titania, sitting upon the transparent conductive oxide fluorine-doped tin oxide (FTO). With this double collection layer we have reached up to 17.9% power conversion efficiency, delivering a stabilized power output (SPO) of 17.0%, measured under simulated AM 1.5 sunlight of 100 mW cm–2irradiance. Finally, we propose a mechanism of the charge transfer processes within the fabricated architectures in order to explain the obtained performance of the devices.

In recent years, organo-lead-halide perovskites have emerged as promising new materials for photovoltaics, reaching high efficiencies. The excellent photoelectronic properties and easy solution processing makes the lead perovskite an ideal light harvesting material in a solar cell. In spite of these great advantages, there are concerns about the lead contained in the material because of its well-known toxicity characteristics. Obtaining new metal halide perovskites without lead is still a challenge; until now, only a few experimental reports have been published and some other theoretical calculations replacing lead by most of the possible candidates of the periodic table. In this paper, we show for the first time synthesis of the calcium hybrid perovskites CH3NH3CaI3and CH3NH3CaI3–xClxwith complementary studies based on first-principles band-structure calculation. Crystallographic analysis shows a pseudocubic structure, and optical measurements confirms that this type of perovskite absorbs light in the UV region, which is in good agreement with the calculation that showed a band gap larger than 3.5 eV.

Perovskite solar cells (PSCs) have been extensively studied in recent years due to their unexpected properties and low-temperature processing. In terms of morphology, the annealing conditions are crucial and highly determinant on the performance of the devices. Here, it is important to know the heat transfer in order to prevent detrimental effects in the photovoltaic performance principally produced by low crystallization and localized excessive thermal stress in the synthesized perovskite. In this work, differential scanning calorimetry (DSC) was used to reveal the thermal transitions occurring during crystallization of a mesoporous alumina-based PSC. We found that when the mixed-halide perovskite (CH3NH3PbI3–xClx) is crystallized in the presence of a mesoporous layer, the heat transfer flux is affected and therefore the perovskite formation shifts to higher temperatures, causing the infiltrated perovskite to crystallize differently than the capping layer. DSC analysis also indicated that when low annealing temperatures were used, the perovskite did not present good crystallinity, while at high temperatures the thermal stress generated on the infiltrated perovskite promoted low efficiencies. Finally, the optimal crystallization conditions were found to be 100 °C for 90 min, with a short postannealing at 130 °C for 10 min, which promoted a photoconversion efficiency up to 10.89%.

Controlling the nature and transfer of excited states in organic photovoltaic (OPV) devices is of critical concern due to the fact that exciton transport and separation can dictate the final performance of the system. One effective method to accomplish improved charge separation in organic electronic materials is to control the spin state of the photogenerated charge-carrying species. To this end, nanoparticles with unique iron oxide (Fe3O4) cores and zinc oxide (ZnO) shells were synthesized in a controlled manner. Then, the structural and magnetic properties of these core–shell nanoparticles (Fe3O4@ZnO) were tuned to ensure superior performance when they were incorporated into the active layers of OPV devices. Specifically, small loadings of the core–shell nanoparticles were blended with the previously well-characterized OPV active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Upon addition of the core–shell nanoparticles, the performance of the OPV devices was increased up to 25% relative to P3HT-PCBM active layer devices that contained no nanoparticles; this increase was a direct result of an increase in the short-circuit current densities of the devices. Furthermore, it was demonstrated that the increase in photocurrent was not due to enhanced absorption of the active layer due to the presence of the Fe3O4@ZnO core–shell nanoparticles. In fact, this increase in device performance occurred because of the presence of the superparamagnetic Fe3O4in the core of the nanoparticles as incorporation of ZnO only nanoparticles did not alter the device performance. Importantly, however, the ZnO shell of the nanoparticles mitigated the negative optical effect of Fe3O4, which have been observed previously. This allowed the core–shell nanoparticles to outperform bare Fe3O4nanoparticles when the single-layer nanoparticles were incorporated into the active layer of OPV devices. As such, the new materials described here present a tangible pathway toward the development of enhanced design schemes for inorganic nanoparticles such that magnetic and energy control pathways can be tailored for flexible electronic applications.

Energy alternatives have been one of the most important research focal areas of the last decade due to the imminent lack of fossil fuels. This motivation has allowed the evolution of the materials science field in areas such as electrochemistry, where high availability, low cost and negligible environmental impact are the desired principal qualities. For this reason, as an example of a photoelectrochemical device, we have proposed the use of natural dyes from 37 agro-industrial wastes in dye-sensitized solar cells. We obtained dyes from red cabbage, radish and roselle wastes with a good stability for eight hours with a constant dose of UV radiation at 60 °C. In these, a strong copigmentation effect was observed at 90 °C in a few hours. Besides which, an increase in the absorption spectra close to 200% was reached with the media extraction proposed. Additionally, the fabricated solar devices reached efficiencies between 0.5% and 1.7%.

Energy alternatives have been one of the most important research focal areas of the last decade due to the imminent lack of fossil fuels. This motivation has allowed the evolution of the materials science field in areas such as electrochemistry, where high availability, low cost and negligible environmental impact are the desired principal qualities. For this reason, as an example of a photoelectrochemical device, we have proposed the use of natural dyes from 37 agro-industrial wastes in dye-sensitized solar cells. We obtained dyes from red cabbage, radish and roselle wastes with a good stability for eight hours with a constant dose of UV radiation at 60 °C. In these, a strong copigmentation effect was observed at 90 °C in a few hours. Besides which, an increase in the absorption spectra close to 200% was reached with the media extraction proposed. Additionally, the fabricated solar devices reached efficiencies between 0.5% and 1.7%.

•Thermal reliability of CA/MA, LA/MA and PA/SA, and their SS-PCMs, was studied.•Thermal cycling was performed up to 10000 cycles, simulating 30 years of application.•Chemical changes and thermal properties were studied after 10, 100, 1000 and 10000 cycles.•The eutectics and their SS-PCMs presented good chemical stability up to 10000 cycles.

•Influence of thermal treatments on the porosity of a support for SS-PCM was studied.•Impregnation of PCMs in supports with various textural properties were carried out.•SS-PCM with support at 600 °C showed the best performance in leakage and latent heat.•CA:MA, LA:MA and PA:SA were shape-stabilized with a leakage below 4.5%, after 16 h of cycling.

•Complete experimental data of the thermal properties of eutectic mixtures capric-myristic (CA:MA), lauric-myristic (LA:MA) and palmitic-stearic (PA:SA) acids were obtained.•Shape-stabilization of CA:MA, LA:MA and PA:SA was achieved in a clay mineral support, thus preventing the leakage of the phase change materials.•Empirical equations of heat capacity as a function of temperature, for the binary eutectics and SS-PCMs, were proposed.

•Bibliometric analysis was carried out for encapsulation and shape-stabilization of organic PCM.•A systematic review was performed for the materials and methods used in CS-PCM and SS-PCM.•Research is heading to new production techniques with organic and inorganic supporting materials.•Opportunities to investigate in leakage, heat capacity, thermal conductivity and thermal cycling.

•Several characterization techniques were used to identify crystalline and non-crystalline mineralogic phases from a Colombian natural occurring material.•The Colombian mineral included diatomite that can be used as a porous support.•A low leakage shape-stabilized phase change material was developed.