Energy Conversion Applications Research Articles

Investigating the impact of various etching agents on Ti3C2Tx MXene synthesis for electrochemical energy conversion

MXenes represent a revolutionary class of two-dimensional (2D) materials that have garnered significant attention due to their unique properties, including excellent electrical conductivity, and remarkable mechanical strength. This study investigates the influence of different etching agents on the synthesis of MXenes for electrochemical energy conversion applications, particularly in methanol oxidation reactions (MOR). Morphological characterization, particle distribution and sizing, elemental analysis, and surface chemistry assessments were conducted using field emission scanning electron microscopy (FESEM), elemental mapping, transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). Electrochemical techniques such as cyclic voltammetry (CV), electrochemical active surface area (ECSA), Tafel analysis, electrochemical impedance spectroscopy (EIS), and long-term stability assessment were employed. The study reveals that PtRu/MXene synthesized with the FeF3/HCl etching route exhibits the highest ECSA value and peak current density, being 12.3 times and 3.63 times higher than those achieved via the LiF/HCl etching route. The kinetic rate, tolerance to catalyst poisoning and long-term stability also show the better results for this etching route. These findings suggest promising potential for PtRu/MXene_FeF3/HCl as an effective anodic electrocatalyst in direct methanol fuel cell (DMFC) applications.

Hydrogels and Aerogels for Versatile Photo-/Electro-Chemical and Energy-Related Applications.

The development of photo-/electro-chemical and flexible electronics has stimulated research in catalysis, informatics, biomedicine, energy conversion, and storage applications. Gels (e.g., aerogel, hydrogel) comprise a range of polymers with three-dimensional (3D) network structures, where hydrophilic polyacrylamide, polyvinyl alcohol, copolymers, and hydroxides are the most widely studied for hydrogels, whereas 3D graphene, carbon, organic, and inorganic networks are widely studied for aerogels. Encapsulation of functional species with hydrogel building blocks can modify the optoelectronic, physicochemical, and mechanical properties. In addition, aerogels are a set of nanoporous or microporous 3D networks that bridge the macro- and nano-world. Different architectures modulate properties and have been adopted as a backbone substrate, enriching active sites and surface areas for photo-/electro-chemical energy conversion and storage applications. Fabrication via sol-gel processes, module assembly, and template routes have responded to professionalized features and enhanced performance. This review presents the most studied hydrogel materials, the classification of aerogel materials, and their applications in flexible sensors, batteries, supercapacitors, catalysis, biomedical, thermal insulation, etc.

Development of Wood-Based functional composites for advanced sensing and energy conversion applications

With the low carbon-driven development of modern intelligent, research towards novel materials is concentrating on the sustainable biomass-based advanced functional composites. The advanced functionalized wood toward sensing, optoelectronic devices, and energy conversion has been contributed to fast electron transport upon temperature or photo stimulus. Fast electron transport has been highly depended on the interfacial adhesion between the functional layer and wood matrix as well as graphitization degree during carbonization, which promote the electronic excitation and jumps. Here, we develop wood-based functional composites for advanced fire warning and energy conversion by loading metal–insulator transition (MIT) function factor (Ti3O5) onto different woods via liquid crosslinkers, and systematically establish the interfacial adhesion-carbonization-electron transport processes and their relationships on the sensing and photothermal conversion properties. Firstly, balsa with high porosity (pore diameter ≈50 μm), low density (0.16 g/cm3) and extractives content (total extractives content 16.27 %) facilitates crosslinker penetration due to the more holding space and lower nonpolar components. A favorable permeation can promote better interfacial adhesion, and the formation of a continuous conductive network of char-layers during carbonization. Secondly, the crosslinker (chitosan) with excellent adhesion (1 level) and char-forming ability (char residues is 21.7 %), facilitates the formation of a compact network of highly graphitized char-layers (ID/IG=0.81), which increases the electrical conductivity (highest conductivity 5.52 × 10-4 S/m). We found that the most sensitive flame trigger time (0.86 s) for fire warning and the highest evaporation flux (1.63 kg m-2h−1) for desalination can be obtained by using balsa which coupled the chitosan as well as the Ti3O5.

A DFT Calculations of Mechanical, Optoelectronic and Transport Properties of Cubic AMgI3 (A = Li/Na) Halides for Photovoltaic and Energy Conversion Applications

A DFT Calculations of Mechanical, Optoelectronic and Transport Properties of Cubic AMgI3 (A = Li/Na) Halides for Photovoltaic and Energy Conversion Applications

Intrinsic single-layer multiferroics in transition-metal-decorated chromium trihalides

Two-dimensional materials possessing intrinsic multiferroic properties have long been sought to harness the magnetoelectric coupling in nanoelectronic devices. Here, we report the achievement of robust type I multiferroic order in single-layer chromium trihalides by decorating transition metal atoms. The out-of-plane ferroelectric polarization exhibits strong atomic selectivity, where 12 of 84 single-layer transition metal-based multiferroic materials possess out-of-plane ferroelectric or antiferroelectric polarization. Group theory reveals that this phenomenon is strongly dependent on p–d coupling and crystal field splitting. Cu decoration enhances the intrinsic ferromagnetism of trihalides and increases the ferromagnetic transition temperature. Moreover, both ferroelectric and antiferroelectric phases are obtained, providing opportunities for electrical control of magnetism and energy storage and conversion applications. Furthermore, the transport properties of Cu(CrBr3)2 devices are calculated based on the non-equilibrium Green’s function, and the results demonstrate outstanding spin-filtering properties and a low-bias negative differential resistance (NDR) effect for low power consumption.

Eu-viologen based bimetal–organic frameworks nanosheets with Mn atoms anchored on Eu-µ-O skeletons as high-performance negative electrode for flexible asymmetric supercapacitors

Exploring advanced negative electrode materials is imperative to develop high-performance asymmetric supercapacitors for breaking through current energy density limits of supercapacitors, but remains challenging. Herein, a strategy is proposed to create a novel negative electrode by anchoring Mn single-atoms on Eu-viologen metal–organic frameworks (EV-Mn MOFs) nanosheets flowery architectures that self-supported on oxidized carbon cloths (OCC). Such EV-Mn/OCC achieves a negative broadened voltage window (−1 ∼ 0 V) and boosted areal capacitance (840.82 mF cm−2), which is four folds of the isostructural EV/OCC without Mn atoms and surpasses most of currently reported negative electrodes. Also, the EV-Mn/OCC manifests good cycling stability (∼80 % retention for 10,000 cycles). As deduced by the thorough studies of X-ray absorption fine spectra and X-ray photoelectron spectroscopies, the enhanced pseudocapacitance of EV-Mn/OCC definitely correlates to the valence modulation of Mn and Eu through internal electron transfer via Eu-O-Mn bonds on Eu-µ-O skeleton in EV-Mn MOFs. Subsequently, the constructed flexible all-solid-state symmetric supercapacitors employing EV-Mn/OCC as negative electrode can deliver a high energy density (86.89 μWh cm−2) at 1600 μW cm−2, outperforming many asymmetric devices based on traditional negative electrode materials. This work can spur the development of single-atom metallic electronic-modulation strategy for MOFs negative electrode material (MOFs-NEM), and accelerate their applications in flexible energy conversion and storage devices.

Advancing photocatalytic degradation under visible light with TiO2/g-C3N4 nanohybrid mechanistic insights

In this study, we presents a novel method for bolstering the photocatalytic effectiveness of crystalline titanium dioxide (TiO2) through the integration of graphitic carbon nitride (g-C3N4), creating a series of TiO2/g-C3N4 nanohybrids (TiCN-NHs). Leveraging an economical and scalable pyrolysis technique, we crafted different ratios of these nanohybrids (TiCN-NHs-1, TiCN-NHs-2, TiCN-NHs-3, and TiCN-NHs-4) to optimize their performance in harnessing visible light for photocatalysis. Detailed spectroscopic examinations were performed to dissect the nanohybrids’ structural and morphological nuances, alongside their chemical interactions and states. The primary evaluation of these nanohybrids’ photocatalytic prowess was the degradation of a selected colored organic contaminant under visible light exposure. The TiCN-NHs showcased an unprecedented photocatalytic degradation efficiency, surpassing that of p-TiO2 and bulk b-g-C3N4 by twelvefold and eightfold, respectively, under comparable conditions. This dramatic increase in photocatalytic activity is credited to the harmonious interface between TiO2 and g-C3N4 within the nanohybrids, fostering a diminished bandgap and promoting efficient charge separation. Additionally, photoluminescence and density of state analyses, specifically focusing on valence band spectra under visible light irradiation, further confirmed these findings. The synergistic effects observed in TiCN-NHs not only enhance photocatalytic degradation rates but also spotlight the potential of these nanohybrids in solar energy conversion and environmental cleanup applications, offering a promising avenue for future research in sustainable technologies.

(Invited) Manipulation of Locally-Excited, Charge-Transfer, and Charge-Separated States at Organic-Inorganic Heterointerfaces

Precise engineering of excited-state interactions between an organic conjugated molecule and a two-dimensional semiconducting inorganic nanosheet, specifically the manipulation of locally-excited (LE), charge-transfer (CT), and charge-separated (CS) states, still remains a challenge for state-of-the-art photochemistry. In this study we successfully observed a long-lived, highly emissive CT state at structurally well-defined hetero-nanostructure interfaces of photoactive pyrene and two-dimensional (2D) MoS2 nanosheet via N-benzyl succinimide bridge (Py-Bn-MoS2). Spectroscopic measurements revealed that the LE state of pyrene in Py-Bn-MoS2 efficiently generates an unusual emissive CT state without further yielding the CS state. Theoretical studies supported the interaction of MoS2 vacant orbitals with the pyrene excited state to form a CT state. This is the first example of realizing a mixing luminescence property of organic–inorganic 2D hetero-nanostructures by an accurate design of bridge structure, and therefore represents an important step in their applications for energy conversion and optoelectronic devices and sensors.[1] J. Baek, T. Umeyama, W. Choi, Y. Tsutsui, H. Yamada, S. Seki, H. Imahori, Chem. Eur. J., 24, 1561 (2018).[2] T. Umeyama, T. Ohara, Y. Tsutsui, S. Nakano, S. Seki, H. Imahori, Chem. Eur. J., 26, 6726 (2020).[3] T. Umeyama, H. Xu, T. Ohara, Y. Tsutsui, S. Seki, and H. Imahori, J. Phys. Chem. C, 125, 13954 (2021).[4] T. Umeyama, D. Mizutani, Y. Ikeda, W. R. Osterloh, F. Yamamoto, K. Kato, A. Yamakata, M. Higashi, T. Urakami, H. Sato, H. Imahori, Chem. Sci., 14, 11914 (2023).

New Charged Interfaces for Energy Conversion and Catalysis

Charged interfaces are key areas for charge transfer and chemical reactions. Studying these interfaces at the microscopic level, especially in constructing and characterizing specific structures, understanding charge transfer, and managing chemical reactions, is crucial but challenging. Our work focuses on three innovative interface structures: solid/solid triboelectric, liquid/gas electrified, and solid/ultrathin heterojunction interfaces. We have achieved significant insights into the charge transfer mechanisms within these electrified systems and effectively controlled catalytic reactions at these interfaces.Key findings include: Development of new concepts for contact electrification and electrostatic-induced coupling at solid/solid interfaces, leading to novel applications in energy conversion and catalysis. We introduced the concept of mechanical-electric-catalytic reactions based on triboelectric interfaces and achieved direct synthesis of hydrogen peroxide through friction-catalysis under normal conditions.Effective control of reaction kinetics and selectivity in charged microdroplet liquid/gas electrified interfaces by adjusting parameters like droplet evaporation rates and electric field characteristics. This approach led to efficient production of hydrogen peroxide and selective conversion of carbon dioxide.Precise atomic-level construction and sub-nanometer characterization of solid/ultrathin heterojunction interfaces, exemplified by gold/graphene interfaces. This included the development of a gold/ultrathin palladium/single-layer ruthenium structure, enabling in-depth study of hydroxylation reactions and the influence of palladium interlayers on ruthenium's catalytic efficiency.

Simulation of Electrical Conductivity of Porous Composite Electrodes for Solid Oxide Cells Using a Monte Carlo 3D Equivalent Electronic Circuit Networks

Solid oxide cells (SOCs) show high potential in energy conversion applications necessary for the decarbonization of the economy. Their advantage consists in ability to operate at high temperatures, reaching up to 900 °C. Firstly, it results in accelerated electrode reactions kinetics, secondly, in favorable thermodynamic conditions decreasing the equilibrium voltage of the water splitting. As a result, SOCs are attractive candidates for both efficient electrolysis and fuel cell applications, offering a robust solution in the pursuit of clean energy. However, the elevated operational temperature also introduces material challenges that hinder the competitiveness of SOCs.Porous gas diffusion electrodes are used to accomplish the desired electrode reactions. Considering conventional exclusively electron-conductive electrode materials, triple phase boundary (TPB) is required for the reactions to take place – a simultaneous contact of electron-conductive, ion-conductive and gaseous phase. While the electrode and electrolyte phases are solid, the gaseous phase is represented by open porosity in the electrode body. TPB is located exclusively at the contact area of electrode and electrolyte components in the case of single-phase electrodes, limiting the electrode electrocatalytic performance. To avoid the limitation by TPB length, composite electrodes are frequently used. Due to the involvement of the ionically conductive phase, they exhibit improved electrocatalytic capabilities.Electrolyte phase, however, usually exhibits 4 orders of magnitude lower electrical conductivity than the electron-conductive phase, while gaseous phase is electrically non-conductive. Thus, an improper phase composition and morphology of the composites can lead to a significant drop in their electrical conductivity and thus in the cell performance. Simple and reliable method for the conductivity value prediction is up to now missing. At the same time, experimental determination is both expensive and time-consuming. The goal of this study was to develop simple, fast and reliable method for prediction of electrical conductivity of the porous electron-ion conductor composites.The key feature of the presented approach lies in the minimal requirements for input parameters. Only electrode phase composition and bulk electrical conductivity of each phase are required. Based on the input composition, the model generates a 3D artificial specimen, a domain discretized into cubic voxels each assigned randomly to a specific phase. The resulting structure is substituted with an equivalent circuit network with electric elements corresponding to the electrochemical properties of the material components: specific resistivity of electrical conductors and polarization resistance / capacitance of electrochemical reaction at material interface. In-silica electrochemical impedance spectroscopy measurement is performed by solving charge balance following Kirchhoff’s current law for multiple frequency values. Resulting impedance spectrum is fitted in order to obtain Ohmic and polarization resistance and the capacitance of the artificial specimen. This procedure is averaged over a large number of artificial specimens in a Monte Carlo manner.Conventionally used oxygen electrode composite material lanthanum strontium manganite (LSM) mixed with yttria-stabilized zirconia (YSZ) was used to produce validation dataset. LSM:YSZ powder mixtures of compositions between 1:0 and 0:1, chosen to produce samples of various degree of LSM percolation, were homogenized. The mixtures were fired at 1150 °C. Electrical conductivity of the pellets was determined at temperatures between 600 and 800 °C using electrochemical impedance spectroscopy.Experimental data obtained were confronted to the model results. The model demonstrated very good accuracy for a porosity value of up to 55%. Significant error was observed in the porosity range between 55% and 68%. Finally, the model failed to generate an artificial specimen with a porosity of 75%. As it was found, the limited applicability of the model for the materials characteristic for high porosity was caused by the coalescence of the void phase. This shortcoming of the model was solved by implementing morphological parameter describing degree of void phase coalescence in the electrode structure. Due to this modification, model allows to gain valuable information on the microstructure of the studied composite material on the base of the experimentally determined conductivity data.This work introduces a novel modelling approach with minimal amount of input parameters, streamlining the prediction of electrical conductivity of porous electron-ion conductor composites. This simplified yet effective methodology holds great promise for efficiently characterizing and optimizing materials for energy conversion applications, offering a valuable tool for advancing research in the field.This publication was supported by the project "The Energy Conversion and Storage", funded as project No. CZ.02.01.01/00/22_008/0004617 by Programme Johannes Amos Commenius, call Excellent Research.

Enhanced Electrochemical Performance of Double Perovskites as Cathodes in Reversible Ceramic Electrochemical Cells through Nb Doping

Efficient and cost-effective generation of electricity and hydrogen holds promise through reversible protonic ceramic electrochemical cells (R-PCECs). However, the successful commercialization of R-PCECs depends on the advancement of air electrodes that are both highly active and durable. Here, we made an air electrode material with two phases of double perovskite and single perovskite by doping Nb into B-site of the traditional PrBaCo2O6 double perovskite. The coexistence of the mixed double perovskite and single perovskite phases demonstrates superior electrochemical performance and durability compared to pristine double perovskite and single perovskite materials when employed as cathode materials. X-ray photoelectron spectroscopy (XPS), synchrotron radiation X-ray absorption spectroscopy (XAS) and neutron diffraction analysis reveal that this enhancement is primarily attributed to the introduction of high-valence Nb5+, resulting in an increased number of oxygen vacancies and structural stability. The findings presented in this study contribute valuable insights into the design and development of advanced cathode materials for solid oxide fuel cells and electrolyzers, with the potential for applications in sustainable energy conversion and storage technologies.

(Invited) Ternary Oxide Semiconductors and Alloys for Photoelectrochemical Applications: Hope and Reality

This perspective talk focuses on the history and status of new materials with targeted application in solar energy conversion. Specifically, photoelectrochemical energy conversion/solar water splitting and wide bandgap oxide semiconductors and alloys for solar windows and displays are the two targeted application areas. The Cu-M-V-O family of oxide semiconductors will be discussed in this talk. Both synthetic aspects and chemical composition-property-performance correlations will be presented.Acknowledgements. This work was primarily supported by the National Science Foundation UTA/NU Partnership for Research and Education in Materials (NSF DMR-2122128).

Lattice Symmetry-Guided Charge Transport and Recombination in Supramolecular Assemblies

Synthetic soft materials mimicking biological structures are promising for many applications in fields such as photovoltaics and photocatalysis. For these applications, a deep understanding of the charge- and energy-transfer mechanisms is required to build more efficient devices. In this work, we investigate self-assembled 2D supramolecular structures using angle-resolved photoluminescence (PL) imaging techniques and decompose the optical transition dipoles in the supramolecular structures. Combining these optical studies with Monte Carlo simulations, we reveal the important role played by lattice symmetry in charge dissociation, transport, and recombination, as well as the exciton spin states. These mechanistic findings have important implications for engineering soft materials towards efficient energy conversion and photocatalytic applications.

(Invited) Electron Transport in Nanocarbon Networks for Energy Conversion and Storage Applications

Carbon nanostructures have attracted great attention in recent years as novel electrode materials in batteries with increased capacity and conductivity as well as enhanced material stability. In these nanostructures, nanocarbons such as carbon nanotubes and graphene nanoplatelets are interconnected to construct their three-dimensional networks around the host materials for Li deposition. This work focuses on the study of electron transport phenomena in these nanocarbon networks with two model material systems: (1) single-walled carbon nanotube (SWCNT) networks co-embedded with silica microparticles (Fig. (a)), and (2) free-standing three-dimensional graphene (3DG) structures with polymeric surface modifications (Fig. (b)). We characterize the materials for electrical conductivity and thermopower with varying material contents in the composites to reveal several key factors determining their energy-dependent carrier transport characteristics. It is found that in these three-dimensional nanocarbon networks, carrier tunneling at the junctions between nanocarbons along with the network morphology predominantly determines the transport properties. Simultaneous increase in electrical conductivity and thermopower is achieved for SWCNT networks co-embedded with silica microparticles by increasing silica content up to 40 w.t.% at a fixed CNT content. The enhanced electron transport is attributed to the reduced junction distances due to the intimate network formation on the surface of silica particles with a polymer binder. Our transport theory based on the Landauer formalism for junction tunneling reveals that the junction modification with polymer can alter the potential barrier heights for both electrons and holes at the junction to significantly change the transport properties of the composite. Doping of nanocarbons is also investigated for their impacts on the junction transport and the geometric factor of the networks. Finally, we also investigate the use of these carbon nanostructures in solid-state thermoelectric (TE) energy harvesters and ionic TE capacitors to harvest thermal energy from temperature gradients and fluctuations. Figure 1

Electrochemistry of 2D Nanosheets Based on Platinum Group Metals

Electrocatalysts and electrode materials based on platinum group metal (PGMs) and thier oxides are one of the most well studied materials for energy storage and conversion applications.1,2 As such materials are scarce, downsizing is critical for practical applications and various nanomaterials have been synthsized so far. 2D nanostructures (nanosheets) are particularly promising, owing not only to the high surface/volume ratio, but also to the stability originating from the 2D extended bonds. This talk will attempt to provide a summary of state-of-the-art PGM nanosheets and a critical assessment on the possible applications of such innovative nanomaterials. We will present and discuss recent advancement on the synthesis and structure-property relation of PGM oxide nanosheets based on RuO2 and IrO2 for supercapacitor3-5 application as well as electrocatalysts.6,7 In addition, electrocatalytic activity of Pt and core-shell Pt nanosheets will be presented.8-11 1. W. Sugimoto, Electrochemistry, 86, 281–290 (2018) DOI: 10.5796/electrochemistry.18-6-E2668.2. W. Sugimoto and D. Takimoto, Chem. Lett., 50, 1304–1312 (2021) DOI: 10.1246/cl.210087.3. W. Sugimoto, H. Iwata, Y. Yasunaga, Y. Murakami, and Y. Takasu, Angew. Chem. Int. Ed., 42, 4092–4096 (2003) DOI: 10.1002/anie.200351691.4. K. Fukuda, T. Saida, J. Sato, M. Yonezawa, Y. Takasu, and W. Sugimoto, Inorg. Chem., 49, 4391–4393 (2010) DOI: 10.1021/ic100176d.5. K. Sonobe, S. Tominaka, and W. Sugimoto, J. Am. Chem. Soc., 144, 15008–15012 (2022) DOI: 10.1021/jacs.2c05951.6. D. Takimoto, K. Fukuda, S. Miyasaka, T. Ishida, Y. Ayato, D. Mochizuki, W. Shimizu, and W. Sugimoto, Electrocatalysis, 8, 144–150 (2017) DOI: 10.1007/s12678-016-0348-4.7. D. Takimoto, Y. Ayato, D. Mochizuki, and W. Sugimoto, Electrochemistry, 85, 779–783 (2017) DOI: 10.5796/electrochemistry.85.779.8. K. Fukuda, J. Sato, T. Saida, W. Sugimoto, Y. Ebina, T. Shibata, M. Osada, and T. Sasaki, Inorg. Chem., 52, 2280–2282 (2013) DOI: 10.1021/ic302720d.9. D. Takimoto, T. Ohnishi, J. Nutariya, Z. Shen, Y. Ayato, D. Mochizuki, A. Demortière, A. Boulineau, and W. Sugimoto, J. Catal., 345, 207–215 (2017) DOI: 10.1016/j.jcat.2016.11.026.10. J. Nutariya, E. Kuroiwa, D. Takimoto, Z. Shen, D. Mochizuki, and W. Sugimoto, Electrochim. Acta, 283, 826–833 (2018) DOI: 10.1016/j.electacta.2018.07.005.11. D. Takimoto, S. Toma, Y. Suda, T. Shirokura, Y. Tokura, K. Fukuda, M. Matsumoto, H. Imai, and W. Sugimoto, Nat. Commun., 14, 19 (2023) DOI: 10.1038/s41467-022-35616-4.

A Deep Dive into the Study of Nitrogen-Doped Carbons As Electrocatalysts for the Oxygen Reduction Reaction Via a Design of Experiments Approach

Porous nitrogen (N)-doped carbons derived from earth-abundant precursors and exhibiting tunable properties hold promise as low-cost, high-performance electrode materials for energy storage and conversion applications. As metal-free electrocatalysts for the oxygen reduction reaction (ORR) at the cathode in hydrogen fuel cells, N-doped carbons have shown selectivity and performance rivaling that of Pt/C. Alternatively, other N-doped carbons have also demonstrated low overpotentials and high selectivity for the 2-electron pathway of the ORR for the production of hydrogen peroxide. The activity and selectivity of these doped carbons are thought to result from their N-content, N-motifs, and/or porosity. However, the extent to which each of these variables impacts electrocatalytic ORR performance and whether there is an interactive effect between N-content, porous structure, etc. remains unclear. Herein, by implementing a design of experiments approach, the synthesis-structure-function relationship for N-doped carbons prepared via molten salt templating was elucidated to reveal how synthetic handles tune material properties which, in turn, determine electrocatalytic performance. Specifically, the wt% of N precursor and the synthesis temperature were found to have the most significant effect on the N-content and N-motif composition of the resulting N-doped carbons. Regarding porosity, larger surface areas and micropore volumes were realized for the carbons prepared with a larger wt% of N precursor. It was found that surface areas upwards of 300 m2/g were required to see any substantial activity (e.g. half-wave potential greater than 0.7 V vs RHE, effective electron transfer number > 3.4). Only after a threshold surface area was achieved were effects from N-content and N-motifs notable on performance and selectivity.

Elucidating the Impact of the Dielectric Environment on Excitons and Trions in 2D Semiconductor Electrodes

Transition metal dichalcogenides (TMDs) (MX2; M = Mo, W; X = S, Se) are a promising class of materials for photoelectrochemical solar energy conversion applications due to their optimal bandgaps and natural abundance. In this configuration, TMDs are placed onto a conductive substrate and employed as a photoelectrode. A key step in the solar energy conversion process is to photo-excite the semiconductor and dissociate the photogenerated excitons to drive a reaction of interest (e.g., H2 evolution). Because these materials are so physically thin, the excitons are sensitive to the local environment. In this work, we characterize the exciton and trion formation behavior as a function of solvent dielectric, ionic strength, and chemistry. As the dielectric constant of the solvent decreases, trion formation increases. The lower dielectric solvent causes lower Coulombic screening, increasing the probability that an exciton will encounter another electron to generate a trion. I will discuss how these findings relate to a working photoelectrochemical cell.

Effect of Ca, Ba, Be, Mg, and Sr Substitution on Electronic and Optical Properties of XNb2Bi2O9 for Energy Conversion Application Using Generalized Gradient Approximation–Perdew–Burke–Ernzerhof

Bismuth layered structure ferroelectrics (BLSFs), also known as Aurivillius phase materials, are ideal for energy-efficient applications, particularly for solar cells. This work reports the first comprehensive detailed theoretical study on the fascinating structural, electronic, and optical properties of XNb2Bi2O9 (X = Ca, Ba, Be, Mg, Sr). The Perdew–Burke–Ernzerhof approach and generalized gradient approximation (GGA) are implemented to thoroughly investigate the structural, bandgap, optical, and electronic properties of the compounds. The optical conductivity, band topologies, dielectric function, bandgap values, absorption coefficient, reflectivity, extinction coefficient, refractive index, and partial and total densities of states are thoroughly investigated from a photovoltaics standpoint. The material exhibits distinct behaviors, including significant optical anisotropy and an elevated absorption coefficient > 105 cm−1 in the region of visible; ultraviolet energy is observed, the elevated transparency lies in the visible and infrared regions for the imaginary portion of the dielectric function, and peaks in the optical spectra caused by inter-band transitions are detected. According to the data reported, it becomes obvious that XNb2Bi2O9 (X = Ca, Ba, Be, Mg, and Sr) is a suitable candidate for implementation in solar energy conversion applications.

Enhanced bifunctional photocatalytic CO2 reduction and H2 evolution utilizing Cu-doped ZnIn2S4 nanosheets via cation exchange reaction

In this study, Cu-doped ZnIn2S4 nanosheets were synthesized through cation exchange reactions to enhance the dual-functional photocatalytic processes of CO2 reduction and hydrogen evolution. The optimized Cu doping levels in Cu-ZIS samples significantly improved the photocatalytic performance, resulting in enhanced H2-evolution rates and increased selectivity in CO2 reduction, particularly in the production of C2H4 and CO. Characterization techniques confirmed the successful integration of Cu into the ZIS lattice, thereby improving charge transfer and separation within the material. Mechanistic studies indicated that Cu doping enhanced light absorption, charge transfer efficiency, and introduced shallow energy levels, consequently reducing charge carrier recombination and improving overall catalytic performance. These findings highlight the substantial potential of Cu-doped ZnIn2S4 nanosheets for sustainable dual-functional applications in solar energy conversion.

Investigation of Opto-Electronic and Thermoelectric Characteristics of Halide Perovskite CdLiCl3 for Energy Conversion Applications at Different Pressure

Investigation of Opto-Electronic and Thermoelectric Characteristics of Halide Perovskite CdLiCl3 for Energy Conversion Applications at Different Pressure