Modification Of Electronic Structure Research Articles

Modulation of electronic structures and transport properties in 2D TM0.5Ga1.5O3 (TM = Al, Ga, In)

In this study, the band structures, density of states and transport properties of two-dimensional (2D) TM0.5Ga1.5O3 (TM=Al, Ga, In) are investigated by the first principle and the deformation potential theory. Both 2D Al0.5Ga1.5O3 and 2D In0.5Ga1.5O3 alloys tend to form under poor-oxygen conditions. Compared to bulk Ga2O3, the bandgap of 2D Ga2O3 is increased by 0.382 eV and its electron mobility is significantly increased from 143.352cm2·V−1·s−1 to 1486.638cm2·V−1·s−1. For 2D Al0.5Ga1.5O3, the bandgap and the electron effective mass are larger than those of 2D Ga2O3, but its electron mobility is reduced by >25%. In contrast, the bandgap of 2D In0.5Ga1.5O3 is narrower than that of 2D Ga2O3 while its electron mobility is increased by >52%, reaching 2262.901cm2·V−1·s−1. Therefore, 2D In0.5Ga1.5O3 has great potential to be used as a transport material for high-speed Ga2O3 electronic devices.

Facile synthesis of reduced graphene oxide-zirconium oxide/zinc oxide nanocomposites for effective antimicrobial and cytotoxic applications

In this study, reduced graphene oxide (rGO) was successfully synthesised and impregnated with ZrO2-activated ZnO nanoparticles using facile chemical technique to obtain rGO-ZrO2/ZnO nanocomposites for effective biomedical applications. Fourier transform infra-red and X-ray diffraction results were authorized the rGO-ZrO2-ZnO nanocomposites formulation. Scanning electron micrographs showed wrinkled sheets integration of agglomerated spherical grains with hillocks and voids for rGO-ZrO2/ZnO. UV–vis and photoluminescence spectral results proved the modulated electronic structure in the nanocomposites. An extensive investigation was done for synthesised rGO, ZnO, rGO-ZnO and rGO-ZrO2/ZnO against human lung cancer (A549) cell lines. The exposed outcomes revealed the high cytotoxic behaviour against the cancer cell lines by the rGO-ZrO2/ZnO nanocomposites. Moreover, the antimicrobial efficacy of rGO-ZrO2/ZnO nanocomposites exhibited a potential bactericidal effect against S. aureus and E. coli organisms related to rGO-ZnO. Thus, the synthesised rGO-ZrO2/ZnO nanocomposites depicted high, thermal stability and potential bactericidal properties which could be the possible candidate for effective biomedical applications.

Co-Co6Mo6C2 heterostructure grown on carbon nanofibers as tri-functional electrocatalyst for overall water splitting and rechargeable Zn-air batteries

The advancement of cost-effective and efficient electrocatalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is crucial for the progress of clean energy conversion and storage technologies. In this work, cobalt (Co) and cobalt-molybdenum (Mo) bimetallic carbide (Co6Mo6C2) heterostructure grown on carbon nanofibers (denoted as Co-Co6Mo6C2/CNFs) as tri-functional electrocatalyst were prepared by a four-step method. Benefiting from the electronic structure modulation between the heterostructure to improve the catalytic activity, Co-Co6Mo6C2/CNFs exhibits high catalytic activity for HER (91 mV @ 10 mA cm−2), OER (293 mV @ 10 mA cm−2) and ORR (E1/2=0.80 V). Moreover, Co-Co6Mo6C2/CNFs assembled overall water splitting electrolyzer achieves a current density of 10 mA cm−2 with a battery voltage of only 1.70 V and has long-term durability. Zn-air batteries (ZABs) based on Co-Co6Mo6C2/CNFs has a power density of 156.6 mW cm−2 with good stability. This study contributes to the development of inexpensive and efficient transition metal-based multifunctional electrocatalysts.

Exploring the role of redox-active species on NiS-NiS2 incorporated sulfur-doped graphitic carbon nitride nanohybrid as a bifunctional electrocatalyst for overall water splitting

The advancement of effective and robust catalysts that can replace the precious-metal-based benchmarks for electrocatalytic overall water splitting is a highly fashionable approach to exploring sustainable energy utilization and addressing environmental issues. Herein, we demonstrate a facile single-step fabrication of NiS-NiS2 nanoparticles in situ grown on the layered porous sulfur-doped graphitic carbon nitride nanosheets (NiS-NiS2/SGCN) act as bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium.Further, an increasing the Ni precursor (fixed sulfur source) increases the formation of NiS-NiS2 on the surface of SGCN (labeled as NS-1.0, NS-2.0, and NS-3.0). Structural and morphological studies such as PXRD, XPS, FTIR, HR-TEM, etc., revealed a uniform distribution of NiS/NiS2 on the surface of S-g-C3N4 nanosheets. The OER and HER activity of NiS-NiS2/SGCN nanohybrid were significantly enhanced by increasing the affinity of accessible surface-active edge sites, interfacial contact allows effective modification of electronic structure, high structural porosity, redox-active centers of Ni2+/Ni3+, and rich in sulfur vacancy. In addition, the enhancement of the exposure of the edge sites is improved by their attachment to a sulfur-doped g-C3N4 framework. As a result, in the half-cell experiments, the NiS-NiS2/SGCN (NS-3.0) catalyst exhibited enhanced performance in both OER and HER, requiring an overpotential of 298 mV to reach 50 mA/cm2 for OER and −144 mV to reach 10 mA/cm2 for HER. Furthermore, the constructed electrolyzer using Ni-S 3.0 as the cathode and anode required a cell voltage of 1.66 V to yield 50 mA/cm2 in overall water splitting. This study may inspire the in-situ synthesis of different metal sulfides on SGCN to provide a unique interfacial approach for improving the performance of bifunctional non-precious electrocatalysts.

Modulating electron structure of active sites in high-entropy metal sulfide nanoparticles with greatly improved electrocatalytic performance for oxygen evolution reaction

Excellent oxygen evolution reaction (OER) electrocatalysts hold paramount significance for related clean energy conversion technologies. High-entropy materials have garnered significant interests because of their novel structures and unprecedented potentials in application. Herein, we successfully prepared a high-entropy metal sulfide catalyst, specifically (FeCoNiMnMo)Sx, through a facile method. The resulting catalyst exhibited a phase similar to CoS2 and its electrocatalytic activity was rigorously evaluated as an OER catalyst in 1 M KOH. Endowed by the synergistic effect and the modulation of electronic structures among the various metals, the (FeCoNiMnMo)Sx catalyst demonstrated exceptional water oxidation performances. Notably, it required only 290 mV of overpotential to reach 10 mA cm−2. This remarkable performance underscores the effectiveness of high-entropy sulfides as electrocatalysts. The present work supplied a new successful example for exploring the vast potential of high-entropy materials in electrocatalysis and other related fields.

(Invited) Deformable Electronics Based on Strain-Engineered Van Der Waals Materials

Materials exhibit drastically different physical and chemical properties as their dimensionality varies. Atomically-thin van der Waals (vdW) materials possess unique mechanical, electrical, optical, and thermal characteristics, originated from quantum confined low-dimensionality and a lack of dangling bond. In particular, strong in-plane covalent bonding and weak interlayer vdW interaction of two-dimensional (2D) vdW materials enable exceptional combination of mechanical properties, such as high Young’s modulus, high in-plane strength, and ultralow bending stiffness at a level of cell membrane. Moreover, mechanical strain can induce modulation of electronic and phononic band structures of 2D vdW materials more effectively due to mechanical resilience and high surface-to-volume ratio. For these reasons, deformation engineering has garnered substantial interest in mechanics, materials and electronics communities as a new tuning knob for emerging phenomena and functionalities of 2D vdW materials. In this talk, I will discuss deformation engineering of 2D vdW materials – (1) active and dynamic deformation strategies, including in-plane interfacial slippage and out-of-plane structural deformation, (2) deformation strain induced phenomena, and (3) emerging device concepts based on deformation engineering of 2D vdW materials.

Development of Fe-Doped Ni2P-POx Electrocatalyst for Oxygen Evolution Reaction

Water electrolysis is extensively researched as a next-generation energy storage method to overcome the intermittency of renewable energy. Electricity generated from renewable sources such as solar and wind power can be converted into pure green hydrogen through water electrolysis. Despite the potential of green hydrogen as a renewable energy storage/carrier medium, the high overpotential resulting from the slow kinetics of oxygen evolution reaction (OER) and the use of expensive noble metals make cost-competitive hydrogen production a significant challenge. Anion exchange membrane water electrolysis (AEMWE) is one method for hydrogen production, offering economic advantages over proton exchange membrane systems as it allows for the use of relatively inexpensive transition metal catalysts like Ni, Fe, and Co due to its alkaline environment.Nickel phosphide (Ni2P)-based catalysts have emerged as highly promising candidates to accelerate the electrocatalytic OER. In particular, the introduction of Fe into Ni2P has been found to induce charge transfer, optimizing the electronic structure and accelerating the OER process. OER catalysts based on transition metal phosphides often exhibit a core-shell structure with phosphide at the core and oxide at the shell during OER measurements. This core-shell structure enhances OER performance through the oxide shell, complementing the deficient electrical conductivity of the phosphide core, resulting in superior catalytic activity and durability. From this perspective, transition metal phosphates are also being studied as electrocatalysts for OER. Phosphates, such as PO3 -, not only promote oxygen adsorbate adsorption but also induce a distorted local metal center geometry that favors OH- adsorption and further oxidation.To address these challenges, this study develops a facile and scalable synthesis of iron-doped nickel phosphide-phosphate (Fe-doped Ni2P-POx) nano-hybrid system as a superior noble-metal free OER powder-catalyst. The utilization of self-filling and pyrolysis approaches facilitates economically viable production of the highly porous phosphide catalyst with a high specific surface area and rough surfaces. X-ray diffractometer, X-ray photoelectron spectroscopy, and electron paramagnetic resonance elucidates the electronic structure modulation, resulting in phosphide-phosphate nano-hybrid structures. Consequently, the catalyst demonstrates excellent OER activity in 1 M KOH, with a significantly low overpotential of 283 mV at 20 mA cm-2, a small Tafel slope of 28.4 mV dec-1, and a superior exchange current density of 8.22 mA cm-2, surpassing state-of-the-art PGM catalysts. Furthermore, its durability over 20 hours indicates its excellent stability, mass transport properties, and mechanical robustness in alkaline media, underscoring its potential as an efficient OER catalyst to facilitate electrocatalytic hydrogen production. Figure 1

(Invited) In Situ x-Ray Spectroscopy for Energy Materials

In response to the worldwide surge in energy demand, the materials scientists devote themselves to the search for clean and sustainable energy. Without the development of cutting-edge renewable energy materials, going green has never been simple. The zero-emission future requires a multifaceted approach. Advanced functional materials for more effective energy conversion, storage, and conservation are the universal focus of energy research. Although the ideas for increasing the efficiency of current energy materials in terms of energy conversion, storage, or conservation are clear and straightforward, they are technically challenging. It is difficult to better engineer materials in an efficient manner for a practical use without knowing the fundamental atomic and electronic structures, particularly how they respond under operating conditions. Synchrotron x-ray spectroscopies, including x-ray absorption and emission spectroscopies are powerful tools to study the local unoccupied and occupied electronic states. In addition, employing the in situ technique permits us to monitor the atomic and electronic structure modulations of the energy material at work. An emerging x-ray spectro-microscopic technique, scanning transmission x-ray microscopy, which provides spatially resolved x-ray spectroscopy. The significance of utilizing x-ray spectroscopy for the atomic and electronic structure characterization of several significant energy material systems, such as advanced nanocatalysts, artificial photosynthesis materials, and smart materials, will be discussed in this presentation. Recent developments of in situ technique, a number of recent studies, and energy science-related Tamkang University (TKU) end-stations at the BL45A and BL27A of TPS will also be presented.

Enhancement of hydrogen evolution activity of CoS2/MoS2 heterostructure catalysts by electronic structure modulation

MoS2 exhibits high catalytic ability; however, its wide band gap (1.73 eV) and poor intrinsic conductivity significantly restrict the enhancement of its catalytic activity. To enhance the electron transfer between the interface of heterojunctions and improve the hydrogen evolution reaction (HER) performance, the paper constructs a CoS2/MoS2 heterostructures by growing CoS2/MoS2-X on carbon cloth (CC) using a straightforward one-step method. It investigates the HER properties of the heterojunctions of various molar ratios of ammonium molybdate to cobalt nitrate. The results indicate that the CoS2/MoS2-X catalyst exhibits excellent electrocatalytic activity (73 mV@10 mA cm−2) and Tafel slope (80.42 mV dec−1) at 1.0 M KOH when the molar ratio of ammonium molybdate to cobalt nitrate is 1:1 (X = 5). CoS2/MoS2-5 exhibits good durability of over 100 h when current densities are 10 and 100 mA cm−2. Density functional theory (DFT) calculations indicate that heterostructures present an optimized Gibbs free energy of hydrogen adsorption (ΔGH*) close to zero, providing insight into the exceptional HER performance. This work provides a simple, effective and innovative strategy for preparing high-activity CoS2/MoS2 catalysts by modulation of electronic structure.

Dual Modulation of Bulk Electronic Structure and Surficial Active Sites in Sea Urchin‐Like MoO2 Nanoreactors Promoting Electrocatalytic Hydrogen Evolution

AbstractElectrocatalytic hydrogen evolution reaction (HER) is a promising strategy for realizing carbon neutralization as well as for the production of green hydrogen. Molybdenum dioxide (MoO2), possesses acid corrosion resistance and near‐metal‐level conductivity, endowing its widespread application in acidic HER. However, due to spatial barriers at the edge of sites and weak H* adsorption, the HER activity of MoO2 is greatly limited. Herein, a sea urchin‐like Pt@N‐MoO2 nanoreactor is designed, in which the bulk electronic structure and surface‐active sites are modulated by N doping and Pt single atoms anchoring, respectively. DFT calculations indicate that Mo─N coupling changes the charge density of Mo atoms, enhances the adsorption of H*, and thus optimizes the Gibbs free energy. The appearance of Pt‐O/N sites compensates for the lack of active sites exposed by MoO2, while promoting the desorption of H2 from the catalyst surface and accelerating the HER process. This work provides an effective strategy for activating inert electrocatalysts to promote energy conversion via a dual modulation strategy of bulk and surface engineering.

In Situ Defect Engineering of Fe-MIL for Self-Enhanced Peroxidase-Like Activity.

Defect engineering is an effective strategy to enhance the enzyme-like activity of nanozymes. However, previous efforts have primarily focused on introducing defects via de novo synthesis and post-synthetic treatment, overlooking the dynamic evolution of defects during the catalytic process involving highly reactive oxygen species. Herein, a defect-engineered metal-organic framework (MOF) nanozyme with mixed linkers is reported. Over twofold peroxidase (POD)-like activity enhancement compared with unmodified nanozyme highlights the critical role of in situ defect formation in enhancing the catalytic performance of nanozyme. Experimental results reveal that highly active hydroxyl radical (•OH) generated in the catalytic process etches the 2,5-dihydroxyterephthalic acid ligands, contributing to electronic structure modulation of metal sites and enlarged pore sizes in the framework. The self-enhanced POD-like activity induced by in situ defect engineering promotes the generation of •OH, holding promise in colorimetric sensing for detecting dichlorvos. Utilizing smartphone photography for RGB value extraction, the resultant sensing platform achieves the detection for dichlorvos ranging from 5 to 300ngmL-1 with a low detection limit of 2.06ngmL-1. This pioneering work in creating in situ defects in MOFs to improve catalytic activity offers a novel perspective on traditional defect engineering.

Cation/anion-doping induced electronic structure modulation of CoMoO4 for enhanced hydrogen evolution

The design and fabrication of high-performance, inexpensive and durable electrocatalyst toward hydrogen evolution reaction (HER) is supremely significant for alleviating energy crisis and environmental concerns, but still remaining challenging. Herein, we develop an experimental work based on etching and reduction strategy to reveal the remarkable effect of cation/anion co-doping in CoMoO4 on its intrinsic HER activity. The CoMoO4 with Fe and B incorporation (Fe/B-CoMoO4) exhibits a current density of 10 mA cm−2 with strikingly low potential of 38 mV coupling with Tafel slope of 51 mV dec-1, and manifesting a robust durability for 100 h with no attenuation, which is comparable to the state-of-the-art commercial Pt/C catalyst. The collective experimental and theoretical findings concomitantly illustrate that the enhanced performances are due to the strong synergistic effect resulting from the co-doping of Fe and B, which plays a pivotal role in finely tuning the electronic structure of CoMoO4, further optimizing the adsorption free energy of H intermediates and shifting the center of the d-band of Fe/B-CoMoO4 away from the Fermi level. This fantastic work highlights the critical role of foreign element incorporating for optimizing electronic structure of transition metal oxides toward HER, and offers valuable guiding principles for rational design of more efficient energy conversion devices.

Electronic structure, photocatalytic and electrochemical performance of chalcogenide quantum dots loaded on reduced graphene oxide: (Cu2MnSnS4/rGO)

In the present article, facile and novel synthesis of Cu2MnSnS4/reduced-graphene (CMTS/rGO) nanocomposites is achieved. X-ray diffraction (XRD), Raman analysis, X-ray photoelectron spectroscopy (XPS) were explored to test the supposed formation. CMTS semiconductors grow within a tetragonal symmetry and rGO crystallize into hexagonal phase. CMTS particle size is very small having dimensions around 10–12 nm and corroborates with the average particle size calculated from the SEM. The TEM micrograph of rGO consists ∼10 nm thick nanosheets. The composite materials exhibit 2D morphology with 17 nm thick rGO nanosheets holding CMTS quantum dots (9 nm). Electronic structure modulations with rGO specify the replication of energy band gaps with experimental agreements. Photocatalytic activity against malachite green (MG) enhances from 74 % (CMTS) to 95 % (CMTS/rGO). In addition, the electrochemical measurements demonstrate the specific capacitance for 10 % CMTS/rGO (870 F/g) is about four times larger than that of pure CMTS (268 F/g). Our results prompt the evidence of possible applications and further research in photocatalysis via graphene reduction.

Enhancing interfacial electron transfer through PANI electron bridge for tailoring dynamic reconstruction and achieving high-performance water oxidation

Tailoring the dynamic reconstruction of transition metal compounds into highly active oxyhydroxides through surface electron state modification is crucial for advancing water oxidation, yet remains a formidable challenge. In this study, a unique polyaniline (PANI) electron bridge was integrated into the metal–organic frameworks (MOFs)/layer double hydroxides (LDHs) heterojunction to expedite electron transfer from MOFs to LDHs, facilitating electron accumulation at the metal sites within MOF and electron-deficient LDHs. This configuration promotes the surface dynamic reconstruction of LDHs into highly active oxyhydroxides while safeguarding the MOF from corrosion in harsh environments over extended periods. The optimized electronic structure modification of both MOFs and LDHs enhances reaction kinetics. The superior MIL-88B(Fe)@PANI@NiCo LDH catalyst achieved 10 mA∙cm−2 at an overpotential of 202 mV and demonstrated stable operation for 120 h at this current density. This research introduces an innovative approach for guiding electron transfer and dynamic catalyst reconstruction by constructing a PANI electron bridge, potentially paving the way for more efficient catalytic systems.

Triggering Redox Active Sites Through Electronic Structure Modulation in rGO Encapsulated Mixed Transition Metal Oxides Hybrid for Alkaline Hydrogen Evolution.

Designing and developing noble-metal-free catalysts are of current interest in clean hydrogen generation via water splitting. As carbonaceous species are ideal choices as templates for various electrocatalysis, an improved synthetic route and an in-depth understanding of their electrochemical performance are essential. Herein, we have investigated the catalytic performance of rGO-encapsulated Mn and V mixed oxide hybrid structures (MVG) on a NiFeP matrix, focusing on their potential for catalyzing hydrogen evolution in an alkaline environment. The hierarchical MVG hollow microspheres hybrids are synthesized via a simple one-step in situ solvothermal method and MVG/NiFeP coatings are developed by facile electroless plating technique. As evidenced from the X-ray photoelectron spectroscopy, the multiple redox active sites in the 3d-band of Mn and V in MVG hybrid structural coatings serve as electron pumps, and rGO facilitates electronic conductions during catalytic reactions. The modulated electronic structure and strong synergistic effects between NiFeP and MVG facilitate rapid electron transfer kinetics, and the hybrids demonstrate superior HER performance. Consequently, the structural hybrid coatings possess an enhanced electronic conducting path (lower RCT = 545.3 Ω) and large ECSA values with a lower overpotential of 85 mV at 10 mA cm-2 and a reduced Tafel slope of 64.1 mV dec-1 with Volmer-Heyrovsky mechanism in alkaline media.

Switching approximate insulator into semiconductor: Ultrasensitive and rapid triethylamine detections based on In3+ inserted MOF-76 (Nd) derived nanocomposites

Triethylamine (TEA) poses significant risks to both environmental quality and human health. Hence, in this work, we employed an ionic-inserted MOF-derived method to synthesize Nd2O2CO3-based nanocomposites. Electronic structure modulations of Nd2O2CO3 from approximate insulators into semiconductors were realized by In3+ intercalations, which profoundly reduces bandgap and facilitates electron transferring. Adequate oxygen vacancies and Lewis acidity sites in Nd2O2CO3 provide more active sites for TEA reactions. Leveraging defect engineering and electronic structure modulation, the optimized sensor exhibited a considerable TEA response (167.94), rapid responding/recovering (5/42 s) at low temperature (160 ℃). Furthermore, the intensive CO2 adsorption capabilities of Nd2O2CO3 and the abilities to react between TEA and CO2 were confirmed by In-situ DRIFTS thereby certificating the availability of sensors in an atmospheric environment with exceptional anti-interference capability. This work not only develops novel TEA sensing materials but also proposes feasible strategies for optimizing TEA sensing characteristics through ion intercalation.

Proton Conducting Neuromorphic Materials and Devices.

Neuromorphic computing and artificial intelligence hardware generally aims to emulate features found in biological neural circuit components and to enable the development of energy-efficient machines. In the biological brain, ionic currents and temporal concentration gradients control information flow and storage. It is therefore of interest to examine materials and devices for neuromorphic computing wherein ionic and electronic currents can propagate. Protons being mobile under an external electric field offers a compelling avenue for facilitating biological functionalities in artificial synapses and neurons. In this review, we first highlight the interesting biological analog of protons as neurotransmitters in various animals. We then discuss the experimental approaches and mechanisms of proton doping in various classes of inorganic and organic proton-conducting materials for the advancement of neuromorphic architectures. Since hydrogen is among the lightest of elements, characterization in a solid matrix requires advanced techniques. We review powerful synchrotron-based spectroscopic techniques for characterizing hydrogen doping in various materials as well as complementary scattering techniques to detect hydrogen. First-principles calculations are then discussed as they help provide an understanding of proton migration and electronic structure modification. Outstanding scientific challenges to further our understanding of proton doping and its use in emerging neuromorphic electronics are pointed out.

Atomic-level rhodium doping into NiO for boosting the selective electrooxidation of HMF to FFCA in neutral electrolyte

The oxidation reaction of the biomass derivative 5-hydroxymethylfurfural (HMF) holds immense promise for the sustainable synthesis of high-value chemicals. Nevertheless, achieving the selective electrooxidation of HMF to generate high value-added formyl-2-furan carboxylic acid (FFCA) intermediate remains a serious challenge. Here, the V-NiO-Rh catalyst was constructed and demonstrates an impressive FFCA selectivity of 71 % for HMF electrooxidation reaction (HMFOR) in neutral electrolyte. The designed experiments elucidate that the HMFOR mechanism is the co-adsorption of OH* and HMF* on Ni active sites. Furthermore, the theoretical calculations prove that the modulation of Ni electronic structure by single atom Rh promotes the ability of HMF adsorption and the water electrolysis to release OH*. This paper establishes a theoretical foundation for the selective synthesis of high value-added intermediates products that are challenging to obtain in alkaline media.

Nonpyrolytic Fe‐N‐C/Fe2O3 heterostructure with RuO2‐like OER Activity Synthesized via Polyacrylonitrile‐derived Conjugated Pyridinic‐nitrogen‐carbon Sheet

Pyrolytic single Fe atom‐nitrogen‐carbon materials (Fe‐N‐C) and their derivatives are excellent catalysts for electrochemical oxygen reduction reactions. However, they exhibit poor oxygen evolution reaction (OER) activity due to non‐optimal Fe‐O* bonding. This limitation is overcome via electronic structure modulation (i.e., tuning the heteroatom type, concentration, and location within Fe’s n ≥ 1 coordination sphere). However, the methods used are complex and energy‐intensive (i.e., 1000 to 1200°C) raising concerns about reproducibility and cost. This study introduces a method for synthesizing nonpyrolytic Fe‐N‐C/Fe2O3 composites with similar electronic structure modulation as pyrolytic Fe‐N‐C and OER activity akin to commercial RuO2. The methodology involves doping low‐melting hydrated Fe‐salts in electrospun polyacrylonitrile nanofiber to catalyze its transformation into conjugated pyridinic‐N‐rich graphite‐like sheets (i.e., N‐C) at 300°C. N‐C chelate effectively with oxygen‐vacant (Ov)‐rich Fe atoms derived from Fe2O3 NPs resulting in Fe‐N‐C/Fe2O3 heterostructures. The Fe2O3 coupling effectively tunes Fe‐N‐C’s electronic structure via Ov modulation. Consequently, the Fermi and d‐orbital energy levels are optimized leading to partial filling of the antibonding states, optimal Fe‐O* bonding, high electrochemically active surface area, and OER activity. Because Fe‐N‐C/Fe2O3 is synthesized at 300 oC using well‐established techniques, its complexity and cost are favorable compared to pyrolytic Fe‐N‐C materials.

Modulating the electronic structure of macroporous SrTiO3 through cobalt doping for enhance photocatalytic hydrogen evolution

The modulation of electronic structure plays a crucial role in enhancing the adsorption of H* for photocatalytic hydrogen evolution. In this study, we prepared a three-dimensionally ordered macroporous structure of cobalt doping SrTiO3 (Co/3DOMSTO) to provide a large specific surface area that exposes more active sites. The prepared catalysts exhibited the highest rate of photocatalytic hydrogen evolution, reaching 5892.86 μmol g−1 h−1, along with an apparent quantum efficiency (AQE) of approximately 2.4% under illumination at 427 nm. Additionally, the introduction of metal cobalt helped to modulate the electronic structure of Co/3DOMSTO and facilitate spatial charge separation. X-ray absorption fine structure (XAFS) and density functional theory (DFT) calculations were conducted to demonstrate that cobalt occupied the Ti sites on the surface of 3DOMSTO, resulting in changes in the electronic distribution state within space. This phenomenon facilitates the enrichment of electrons at the adjacent Ti sites, making the charge-rich Ti a new active site. These findings underscore the pivotal role played by the geometric configuration and tailored electronic structure of 3DOMSTO in augmenting its photocatalytic performance.