Electronic structure engineering of WO3 by Fe modification for efficient CO2 cycloaddition

Review: 56 refs.

Electronically engineering microstructural design for developing advanced steels: An exploration of high Si bainitic steel

The positive synergies between the metallic 1T-WS2 and Ni2P dual cocatalysts in electronic structure engineering and charge transfer kinetics greatly contribute to the significantly enhanced H2 evolution performance of the ZnIn2S4 catalyst.

Lithium-ion batteries (LIBs) have become the preferred battery system for portable electronic devices and transportation equipment due to their high specific energy, good cycling performance, low self-discharge, and absence of memory effect. However, excessively low ambient temperatures will seriously affect the performance of LIBs, which are almost incapable of discharging at −40~−60 °C. There are many factors affecting the low-temperature performance of LIBs, and one of the most important is the electrode material. Therefore, there is an urgent need to develop electrode materials or modify existing materials in order to obtain excellent low-temperature LIB performance. A carbon-based anode is one candidate for use in LIBs. In recent years, it has been found that the diffusion coefficient of lithium ion in graphite anodes decreases more obviously at low temperatures, which is an important factor limiting its low-temperature performance. However, the structure of amorphous carbon materials is complex; they have good ionic diffusion properties, and their grain size, specific surface area, layer spacing, structural defects, surface functional groups, and doping elements may have a greater impact on their low-temperature performance. In this work, the low-temperature performance of LIBs was achieved by modifying the carbon-based material from the perspectives of electronic modulation and structural engineering.

As promising bifunctional electrocatalysts, transition metal nitrides are expected to achieve an efficient hydrazine oxidation reaction (HzOR) by fine-tuning electronic structure via strain engineering, thereby facilitating hydrogen production. However, understanding the correlation between strain-induced atomic microenvironments and reactivity remains challenging. Herein, a generalized compressive strained W-Ni3N catalyst is developed to create a surface with enriched electronic states that optimize intermediate binding and activate both water and N2H4. Multi-dimensional characterizations reveal a nearly linear correlation between the hydrogen evolution reaction (HER) activity and the d-band center of W-Ni3N under strain state. Theoretically, compressive strain enhances the electron transfer capability at the surface, increasing donation into antibonding orbitals of adsorbed species, which accelerates the HER and HzOR. Leveraging both compressive strain and the modified electronic structure from W incorporation, the W-Ni3N catalysts demonstrate outstanding bifunctional performance, achieving overpotentials of 46mV for HER at 10mA cm-2 and 81mV for HzOR at 100mA cm-2. Furthermore, W-Ni3N catalyst achieves efficient overall hydrazine splitting at a low cell voltage of 0.185V for 50mA cm-2, maintaining stability for ≈450 h. This work provides new insights into the dual engineering of strain and electronic structure in the design of advanced catalysts.

Efficient neutral water splitting may represent in future a sustainable solution to unconstrained energy requirements, but yet necessitates the development of innovative avenues for achieving the currently unmet required performances. Herein, a novel paradigm based on the combination of electronic structure engineering and surface morphology tuning of earth‐abundant 3D‐hierarchical binder‐free electrocatalysts is demonstrated, via a scalable single‐step thermal transformation of nickel substrates under sulfur environment. A temporal‐evolution of the resulting 3D‐nanostructured substrates is performed for the intentional enhancement of non‐abundant highly‐catalytic Ni3+ and pSn2− species on the catalyst surface, concomitantly accompanied with densification of the hierarchical catalyst morphology. Remarkably, the finely engineered NiSx catalyst synthesized via thermal‐evolution for 24 h (NiSx‐24 h) exhibits an exceptionally low cell voltage of 1.59 V (lower than Pt/C‐IrO2 catalytic couple) for neutral water splitting, which represents the lowest value ever reported. The enhanced performance of NiSx‐24 h is a multi‐synergized consequence of the simultaneous enrichment of oxygen and hydrogen evolution reaction catalyzing species, accompanied by an optimum electrocatalytic surface area and intrinsic high conductivity. Overall, this innovative work opens a route to engineering the active material's electronic structure/morphology, demonstrating novel Ni3+/pSn2−‐enriched NiSx catalysts which surpass state‐of‐the‐art materials for neutral water splitting.

The development of artificial photosynthesis for hydrogen peroxide (H 2 O 2 ) production holds considerable practical significance in pivotal fields such as energy conversion and environmental remediation. However, the precise manipulation of photocatalyst electronic structures and the induction of directional photogenerated charge migration remain among the core challenges in this field. Herein, we realized accurate modulation of carbon (C) doping concentrations in carbon nitride (CN) matrices via the introduction of uracil during supramolecular self‐assembly. Based on the regulation of electronic structure and dipole moment, a localized asymmetric carbon nitride photocatalyst (KCCN V ) featuring customized electron traps has been designed and constructed. More importantly, by precisely constructing electronic traps (cyano groups, ─C≡N), novel localized electron‐rich domains are formed to efficiently capture photo‐generated electrons and induce directed carrier migration, thereby significantly suppressing the non‐radiative recombination of photo‐generated electron‐hole pairs. KCCN V achieved an impressive H 2 O 2 production efficiency of 6120.1 µmol g −1 h −1 under oxygen conditions. Furthermore, a Fenton reaction system using H 2 O 2 was constructed in the field to achieve efficient mineralization removal of organic wastewater. This work provides valuable insights into the future solar‐driven H 2 O 2 synthesis and its practical applications, via the rational design of localized asymmetric carbon nitride based on electronic structure engineering.

Facing the increasingly scarce supply of rare-earth resources, a cobalt-doped metal–organic framework-derived carbon–metallic sulfide composite (Co-FeS2@C) was successfully synthesized via the hydrothermal method and the following carbonization/sulfidation treatments and used for the efficient electrosorption of rare earths from aqueous solution. Comparative characterizations revealed that Co doping effectively expanded the interlayer spacing of FeS2, introduced crystalline defects, and optimized the electronic structure, thereby synergistically enhancing active site exposure and electron transfer kinetics. In addition, the electrochemical analysis demonstrated a significant increase in the surface-controlled capacitive contribution from 57.1% to 83.3%, indicating the markedly improved electric double-layer effects and mass transport efficiency. Under the optimal conditions, the Co-FeS2@C electrode achieved a high Yb3+ adsorption capacity of 129.2 mg g−1 along with an exceptional cycling stability (92.63% retention after 20 cycles), substantially outperforming the undoped counterpart FeS2 (88.4 mg g−1 and 74.61%). Furthermore, the mechanistic investigations confirmed that the electrosorption process follows a monolayer physico-chemical synergistic mechanism, primarily driven by the pseudo-capacitive effect arising from the redox reaction of FeS2 and the enhanced charge-transfer driving force resulting from the higher electronegativity of cobalt. This work provides an innovative electronic structure modulation strategy for developing the high-performance capacitive deionization electrodes for rare earth recovery via the electrosorption process.

The electronic structure of the active center of Co3Se4 electrocatalyst was adjusted by Te doping for efficient oxygen evolution

Stacking two-dimensional materials into van der Waals heterostructures with distinct interlayer twisting angles opens up new strategies for electronic structure and physical property engineering. Here, we investigate how the interlayer twisting angles affect the photoluminescence (PL) and Raman spectra of the MoS2/graphene heterostructures. Based on a series of heterostructure samples with different interlayer twisting angles, we found that the PL and Raman spectra of the monolayer MoS2 in these heterostructures are strongly twisting angle dependent. When the interlayer twisting angle evolves from 0° to 30°, both the PL intensity and emission energy increase, while the splitting of the E2g Raman mode decreases gradually. The observed phenomena are attributed to the twisting angle dependent interlayer interaction and misorientation-induced lattice strain between MoS2 and graphene.

The structural and electronic properties of (100) faceted CdTe nanowires with hexagonal or triangular cross sections were investigated using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. The formation energies and band gap of CdTe nanowires are studied as a function of both nanowire size and surface atom ratio. The atomic relaxations of the surface of the (100) CdTe nanowires are compared with the corresponding (100) CdTe surface. The surface strain was eliminated by passivating the dangling bonds with hydrogen atoms. The passivation of the dangling bonds has only little influence on the band gap resulting only in an increase of about 0.06 eV as compared to unpassivated nanowires. However, it had a significant influence on the highest occupied molecular orbital (HOMO) and the lowest unoccupied orbital (LUMO). We also investigated the effect of the adsorption of dicarboxylic acid derivatives on the (100) surface of the hexagonal unpassivated CdTe nanowire with a goal to engineer the band gap. From the band alignment we conclude that the hybrid systems NW-DCDC (di-cyano di-carboxylic acid) and NW-DNDC (di-nitro di-carboxylic acid) represent a type II surface characterized by the presence of molecular states in the gap which reduce the optical gap and may be suitable for use in nanowire-dye sensitized solar cells.

We have investigated the energetic stability and the electronic properties of metal-organic topological insulators bilayers (BLs), $(MC_4S_4)_3$-BL, with M=Ni and Pt, using first-principles calculations and tight-binding model. Our findings show that $(MC_4S_4)_3$-BL is an appealing platform to perform electronic band structure engineering, based on the topologically protected chiral edge states. The energetic stability of the BLs is ruled by van der Waals interactions; being the AA stacking the energetically most stable one. The electronic band structure is characterized by a combination of bonding and anti-bonding kagome band sets (KBSs), revealing that $(NiC_4S_4)_3$-BL presents a Z$_2$-metallic phase, whereas $(PtC_4S_4)_3$-BL may present both Z$_2$-metallic phase or quantum spin Hall phase. Those non-trivial topological states were confirmed by the formation of chiral edge states in $(MC_4S_4)_3$-BL nanoribbons. We show that the localization of the edge states can be controlled with a normal external electric field, breaking the mirror symmetry. Hence, the sign of electric field selects in which layer each set of edge states are located. Such a control on the (layer) localization, of the topological edge states, bring us an additional and interesting degree of freedom to control the transport properties in layered metal-organic topological insulator.

Halide perovskite solar cells are a recent ground-breaking development achieving power conversion efficiencies exceeding 18%. This has become possible owing to the remarkable properties of the AMX3 perovskites, which exhibit unique semiconducting properties. The most efficient solar cells utilize the CH3NH3PbI3 perovskite whose band gap, Eg, is 1.55 eV. Even higher efficiencies are anticipated, however, if the band gap of the perovskite can be pushed deeper in the near-infrared region, as in the case of CH3NH3SnI3 (Eg = 1.3 eV). A remarkable way to improve further comes from the CH3NH3Sn1-xPbxI3 solid solution, which displays an anomalous trend in the evolution of the band gap with the compositions approaching x = 0.5 displaying lower band gaps (Eg ≈ 1.1 eV) than that of the lowest of the end member, CH3NH3SnI3. Here we use first-principles calculations to show that the competition between the spin-orbit coupling (SOC) and the lattice distortion is responsible for the anomalous behavior of the band gap in CH3NH3Sn1-xPbxI3. SOC causes a linear reduction as x increases, while the lattice distortion causes a nonlinear increase due to a composition-induced phase transition near x = 0.5. Our results suggest that electronic structure engineering can have a crucial role in optimizing the photovoltaic performance.

Electrides, featuring localized electrons serving as anionic species, have attracted increasing attention for their catalytic potential. However, their application as supports for hydrogen evolution reaction (HER) electrocatalysts has remained elusive, primarily due to their high chemical reactivity under aqueous conditions. In this study, we report the rational design of a robust electride-supported HER catalyst, Ruthenium (Ru)/Nd2ScSi2, which delivers outstanding performance with an overpotential of only 48 mV at -10 mA cm-2 in 1.0 m KOH, along with excellent long-term stability. In-depth mechanistic investigations, combining in situ spectroscopic analyses with density functional theory calculations, reveal that negatively charged Ru species anchored on the electride surface are pivotal in promoting HER activity. These anionic Ru sites facilitate water dissociation and modulate hydrogen adsorption by reshaping the electronic landscape and tuning the active sites. Our findings highlight the feasibility of leveraging the unique electronic characteristics of electrides to modulate supported metal catalysts, offering a new paradigm for the design of high-efficiency HER electrocatalysts through electronic structure engineering.

Twisted bilayer graphene, a promising material for optoelectronic applications, offers several effective routes toward electronic structure engineering, for example via tuning the relative orientation of the two graphene layers or by varying the distance between them. The so-called collapsed wrinkles, standing, or folded, combine both of these properties. The mutual lattice alignment of the sidewalls of wrinkle leads to formation of a graphene superlattice. Using Raman spectroscopy, we show that the interaction between the sidewalls of the wrinkle and thereby the properties of the twisted multilayer wrinkle can be well tuned by temperature.