Energy advances最新文献

Hydrogen generation through a photocatalytic process appears to be a promising technology to produce this energy vector through a novel, efficient, green, and sustainable process. The fruitful use of sunlight as an excitation source and renewable bio-derived reactants as well as the development of highly efficient catalysts are required to achieve this goal. In this perspective article, we focus on describing how to braid energy and sustainability sides of hydrogen photo-generation into a single parameter, allowing quantitative measurement and trustful comparison of different catalytic systems. Starting from the energy-related efficiency parameters defined by the IUPAC, we present novel approaches leading to parameters enclosing energy and sustainability information. The study is completed with the analysis of other, non-IUPAC, parameters of broad use such as the solar-to-hydrogen observable. The set of results available in the literature for the water splitting reaction and the use of bio-derived sacrificial molecules are reviewed to assess the potential of such reactions in the energy-efficient and sustainable production of hydrogen.

Correction for ‘Acid–base concentration swing for direct air capture of carbon dioxide’ by Anatoly Rinberg and Michael J. Aziz, Energy Adv., 2024, https://doi.org/10.1039/d4ya00251b.

The oxygen evolution reaction (OER) is usually the bottleneck in water electrolysis due to its sluggish kinetics, resulting in increased costs in the production of green hydrogen. Therefore, there is a need for more efficient, stable, and ideally, critical-raw-material-free catalysts. To this end, we have synthesized nanosized spinel ferrites CoFe₂O₄, NiFe₂O₄, and ZnFe₂O₄, and a high-entropy spinel ferrite Zn_0.2Mn_0.2Ni_0.2Co_0.2Fe_2.2O₄ through a simple coprecipitation reaction in an automated reactor on a gram scale. The powder X-ray diffraction and transmission electron microscopy studies revealed crystallite sizes of 20–35 nm. Insight into the oxidation states and cation distribution in the mixed spinel systems was gained through X-ray photoelectron and Mössbauer spectroscopy studies. The activity of all spinel ferrites was tested for the OER through half-cell laboratory measurements and full-cell anion exchange membrane electrolysis (AEMEL), where Zn_0.2Mn_0.2Ni_0.2Co_0.2Fe_2.2O₄ showed the lowest overpotential of 432 mV at a current density of 10 mA cm⁻². All the synthesized ferrites demonstrated good stability up to 20 h, with NiFe₂O₄ being the most active in high current density experiments up to 2 A cm⁻². In addition, studies on the magnetic properties at room temperature revealed a largely superparamagnetic response of the prepared materials, indicating that quantum spin-exchange interactions facilitate oxygen electrochemistry. Computational calculations shed light on the superior catalytic activities of NiFe₂O₄ and Zn_0.2Mn_0.2Ni_0.2Co_0.2Fe_2.2O₄, the two strongly correlated oxides that exhibit the highest magnetization and the smallest band gaps, corroborating the recent principles determining the activity of magnetic oxides in electron transfer reactions.

Fuels can be produced from the electrochemical reduction of industrial waste CO₂ (e-fuels) using renewable energy and hence are an attractive option for the storage of renewable energy in a chemical form. The energy stored in the e-Fuel may be recovered on-demand using a direct fuel cell thus completing a carbon neutral cycle. Anion exchange membrane fuel cells (AEMFCs) are versatile devices that can be fed by both a gaseous fuel such as H₂ and with liquid fuels (e.g. alcohols, formate, hydrazine, NaBH₄). Formate is a molecule that can be easily obtained by the electrochemical reduction of CO₂ with high selectivity. Efficient re-transformation of the energy stored in the chemical bonds into electrical energy requires the development of efficient and stable electrocatalysts. Palladium alloy catalysts are highly active under alkaline conditions when Pd is mixed with more oxophilic transition metals. Here we report that enhanced activity and stability can be obtained with Au–Pd alloy nanoparticles when compared to a Pd catalyst. Both catalysts are prepared by a metal vapour synthesis method. We show that the key to enhanced performance is the partial segregation of Au to the NP surface that increases oxophilicity and favours the adsorption and transfer of OH⁻ species to the active Pd sites. This enhanced activity translates to high power densities and performance stability when employed in AEMFCs fed with aqueous potassium formate fuel (Peak power density of 0.14 W cm⁻², energy efficiency of 33%, faradaic efficiency of 80%).

We introduce operando quantitative electrochemical fluorescence state of charge mapping (QEFSM), a non-invasive technique to study operating electrochemical systems along with a new design of optically transparent microfluidic redox flow cells compatible with the most demanding optical requirements. QEFSM allows quantitative mappings of the concentration of a particular oxidation state of a redox-active species within a porous electrode during its operation. In this study, we used confocal microscopy to map the fluorescence signal of the reduced form of 2,7-anthraquinone disulfonate (AQDS) in a set of multistep-chronoamperometry experiments. Calibrating these images and incorporating an analytical model of quinhydrone heterodimer formation with no free parameters, and accounting for the emission of each species involved, we determined the local molecular concentration and the state of charge (SOC) fields within a commercial porous electrode during operation. With this method, electrochemical conversion and species advection, reaction and diffusion can be monitored at heretofore unprecedented transverse and axial resolution (1 μm and 25 μm, respectively) at frame rates of 0.5 Hz, opening new routes to understanding local electrochemical processes in porous electrodes. We observed pore-scale SOC inhomogeneities appearing when the fraction of electroactive species converted in a single pass through the electrode becomes large.

Polyethylene oxide (PEO)-based polymer electrolytes, despite their cost-effectiveness and ease of processing, suffer from low ionic conductivity at lower temperatures due to the semi-crystalline nature of PEO. Incorporating ceramic filler particles into the polymer matrix offers a potential solution by disrupting its rigid crystalline structure, thereby improving the flexibility of the polymer chains. However, the Li ion conduction pathway within these composite polymer electrolytes (CPEs) remains predominantly within the polymer matrix if the filler particles are only physically mixed. The surface modification of filler particles can improve the interfacial compatibility and ionic conductivity. In this work, two types of filler particles, passive ZrO₂ and active Li₇La₃Zr₂O₁₂ (LLZO), are compared and incorporated into PEO–polyethylene glycol (PEG)–lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) CPEs. The surface of the filler particles is functionalized with a silane ligand ((3-glycidyloxypropyl)trimethoxysilane (GPTMS)) prior to their integration into the PEO matrix. This modifies the interfacial properties between the polymer and the filler particles, hence influencing the ionic conductivity. The functionalized ZrO₂ fillers enhance the ionic conductivity of the CPEs by reducing the crystallinity of PEO. The PEO–PEG–LiTFSI CPE with 15 vol% of GPTMS–ZrO₂ achieved an ionic conductivity of 6.66 × 10⁻⁴ S cm⁻¹ at 20 °C, which is significantly higher than that of the standard PEO–LiTFSI (9.26 × 10⁻⁶ S cm⁻¹). Additionally, coupling GPTMS to PEO chains without the introduction of filler particles also improved the ionic conductivity, while the incorporation of functionalized LLZO fillers does not, which is attributed to a LiCO₃ passivation layer. The results suggest a viable strategy to overcome the inherent limitations of PEO electrolyte, thus offering valuable insights into the design and optimization of CPEs for practical applications.

Unraveling the knowledge of the complex refractive index and photophysical properties of the perovskite layer is paramount to uncovering the physical process that occurs in a perovskite solar cell under illumination. Herein, we probed the optical and photophysical properties of FAPbI₃ (FAPI) and Cs_0.1FA_0.9PbI₃ (CsFAPI) thin films deposited from pre-synthesized powder, by the spectroscopic ellipsometer and time-resolved fluorescence spectra. We determined the complex refractive index of perovskite films by fitting the measured spectroscopic ellipsometer data with the three-oscillator Tauc–Lorentz (T–L) model. We deduced that the CsFAPI thin film had a slightly lower absorption coefficient than the FAPI, but a higher refractive index and dielectric constant than the FAPI. The peak photoluminescence (PL) emission of FAPI and CsFAPI thin film on glass substrates was observed around 803 nm and 799 nm, respectively, while on ITO substrates, both FAPI and CsFAPI thin film was quenched and red-shifted to 816 nm. The methylammonium free pure CsFAPI-based perovskite solar cell fabricated in p–i–n configuration, measured a competitive efficiency of 16.14%, characterized by a J_SC of 23.995 mA cm⁻², V_OC of 912 mV, and FF of 73.74%.

Perovskite solar cells made of inorganic cesium lead bromide (CsPbBr₃) display unusually high open-circuit potentials. Yet, their photovoltaic efficiency is still lagging behind that of iodide-based halide perovskites. In this study, a multistep solution spin coating process is used to create a CsPbBr₃ film. The CsPbBr₃ perovskite film consists of flat and rounded grains, and the photocurrent of each grain type is imbalanced. Interestingly, a significant current increase in flat grains is observed when conducting atomic force microscopy (c-AFM) at the nanoscale after the addition of methyl ammonium bromide (MABr) as an additive. The addition of MABr results in good optoelectronic quality of perovskite films with highly conductive grains and enables better charge transport and hence improved power conversion efficiency.

In this report, we demonstrate a strategy to selectively suppress reactions at unpassivated active material surfaces in silicon composite electrodes, mitigating the capacity-draining effects of continual electrolyte reduction in alloying-type anodes for lithium-ion batteries. Inspired by dipolar modification of electrodes for photovoltaic applications, we introduced conformationally-labile permanent dipoles at the electrochemical electrode interface to dynamically modulate charge transfer kinetics across the interface. Polyacrylic acid (PAA) binder modified with the dipole-bearing molecule 3-cyanopropyltriethoxysilane displays a 17% increase in capacity retention versus unmodified PAA binder. Differential capacity analysis shows a marked cathodic shift of ∼150 mV in overpotential in the pre-alloying voltage range following the initial solid electrolyte interphase (SEI) formation step. At the same time, we observe negligible shift in overpotential for reversible lithium-ion storage, consistent with selective modulation of irreversible reaction kinetics. Electrochemical impedance spectroscopy indicates that this modification results in a thinner SEI layer. Despite the improved performance, the charge transfer resistance of the half-cell is higher with the modification, suggesting some opportunity for improving the strategy. Time-resolved spectroelectrochemical analysis of desolvation kinetics in modified binders indicates that the modified binder has slower and less selective ion transport. We conclude that future iterations of this strategy which avoid disrupting the beneficial ionic transport properties of the binder would result in even greater performance enhancement. We propose that this may be accomplished by incorporating oligomeric dipolar modifiers, either in the binder or at the active material itself. Either way would increase the ratio of dipoles to PAA linking sites, thus avoiding the competing deleterious impacts on device performance.

This study presents a comprehensive cradle-to-gate life cycle assessment (LCA) of synthetic methanol production, integrating low-temperature solid sorbent direct air capture (DAC) systems with renewable energy sources and green hydrogen to evaluate the environmental impacts of various renewable energy configurations for powering the DAC-to-methanol synthesis processes. Renewable energy-powered configurations result in significantly lower greenhouse gas (GHG) emissions than traditional methanol production methods and DAC systems powered by conventional grid energy. Energy configurations analyzed are current US grid mix, solar photovoltaic (PV) in Alabama and Arizona, USA, onshore wind, run-of-river hydroelectric, and geothermal. Notably, hydroelectric and wind power in the western United States emerge as the most sustainable options, showing the lowest global warming potential (GWP) impacts at −2.53 and −2.39 kg CO₂ eq. per kg methanol produced, respectively, in contrast to the +0.944 kg CO₂ eq. from traditional steam methane reforming. Furthermore, this research investigates the use of various heat sources for regenerating low-temperature solid sorbent DAC, emphasizing the potential integration of new experimental results of novel microwave-based regeneration compared to industrial waste heat. Through the analysis of renewable energy scenarios and DAC regeneration heat sources, the research emphasizes the pivotal role of sustainable energy sources in climate change mitigation. This study introduces a new approach by comparing both various renewable energy sources and DAC heat sources to identify the most optimal configurations. This work is also distinguished by its integration of new experimental data on microwave DAC regeneration, offering a unique contribution to the existing body of knowledge. This LCA scrutinizes the environmental impacts of renewably powered DAC-to-methanol systems and compares them with traditional methanol production methods, revealing the significant potential for carbon neutrality. The findings highlight the importance of strategic technology and energy source optimization to minimize environmental impacts, thus guiding the scaling up of DAC and renewable energy technologies for effective climate mitigation. By recognizing the environmental advantages of integrating renewable energy sources with DAC-to-methanol technologies, this research marks a significant step forward in advancing DAC technology and pushes the boundaries of green methanol production toward true sustainability.