Strong Built-in Electric Field Research Articles

BiVO4 Photoanode with NiV2O6 Back Contact Interfacial Layer for Improved Hole-Diffusion Length and Photoelectrochemical Water Oxidation Activity.

The short hole diffusion length (HDL) and high interfacial recombination are among the main drawbacks of semiconductor-based solar energy systems. Surface passivation and introducing an interfacial layer are recognized for enhancing HDL and charge carrier separation. Herein, we introduced a facile recipe to design a pinholes-free BiVO4 photoanode with a NiV2O6 back contact interfacial (BCI) layer, marking a significant advancement in the HDL and photoelectrochemical activity. The fabricated BiVO4 photoanode with NiV2O6 BCI layer exhibits a 2-fold increase in the HDL compared to pristine BiVO4. Despite this improvement, we found that the front surface recombination still hinders the water oxidation process, as revealed by photoelectrochemical (PEC) studies employing Na2SO3 electron donors and by intensity-modulated photocurrent spectroscopy measurements. To address this limitation, the surface of the NiV2O6/BiVO4 photoanode was passivated with a cobalt phosphate electrocatalyst, resulting in a dramatic enhancement in the PEC performance. The optimized photoanode achieved a stable photocurrent density of 4.8 mA cm-2 at 1.23 VRHE, which is 12-fold higher than that of the pristine BiVO4 photoanode. Density Functional Theory (DFT) simulations revealed an abrupt electrostatic potential transition at the NiV2O6/BiVO4 interface with BiVO4 being more negative than NiV2O6. A strong built-in electric field is thus generated at the interface and drifts photogenerated electrons toward the NiV2O6 BCI layer and photogenerated holes toward the BiVO4 top layer. As a result, the back-surface recombination is minimized, and ultimately, the HDL is extended in agreement with the experimental findings.

Efficient Carrier Multiplication in Self-Powered Near-Ultraviolet γ-InSe/Graphene Heterostructure Photodetector with External Quantum Efficiency Exceeding 161.

Carrier multiplication (CM) in semiconductors, the process of absorbing a single high-energy photon to form two or more electron-hole pairs, offers great potential for the high-response detection of high-energy photons in the ultraviolet spectrum. However, compared to two-dimensional semiconductors, conventional bulk semiconductors not only face integration and flexibility bottlenecks but also exhibit inferior CM performance. To attain efficient CM for ultraviolet detection, we designed a two-terminal photodetector featuring a unilateral Schottky junction based on a two-dimensional γ-InSe/graphene heterostructure. Benefiting from a strong built-in electric field, the photogenerated high-energy electrons in γ-InSe, an ideal ultraviolet light-absorbing layer, can efficiently transfer to graphene without cooling. It results in efficient CM within the graphene, yielding an ultrahigh responsivity of 468 mA/W and a record-high external quantum efficiency of 161.2% when it is exposed to 360 nm light at zero bias. This work provides valuable insights into developing next-generation ultraviolet photodetectors with high performance and low-power consumption.

Elucidating the construction and modulation of built-in electric field in the oxygen evolution reaction

The construction of a built-in electric field (BIEF) is considered to be an effective strategy for enhancing catalyst performance due to its critical role in optimizing adsorption of reactants and key intermediates, as well as its positive impact on interface behavior. Herein, a strategy is developed to elucidate the correlation between oxygen evolution reaction activity and the BIEF and its strength by constructing and enhancing the BIEF through incorporating manganese into Co3O4@NiFe-LDH p-n heterojunction. This Co3O4@NiFe-LDH p-n heterojunction generates a BIEF that effectively regulates electronic structure, facilitates rapid electron transfer, induces alterations in the chemical microenvironment, and modulates intermediate adsorption energy. Notably, when hetoroatomic Mn is incorporated into the p-n heterojunction, particularly encapsulated within NiFe-LDH, a more pronounced enhancement for BIEF is observed. Benefiting from this strong BIEF, Co3O4@Mn/NiFe-LDH exhibits excellent OER activity and stability with an overpotential of only 209 mV at 50 mA cm−2, a Tafel slope of 57 mV dec−1, and stable operation for 110 h at approximately 10 mA cm−2. Moreover, density functional theory (DFT) calculations further confirms that the construction and reinforcement of the BIEF can effectively accelerate the electron transfer rates, adjust the metal d-band center, optimize intermediates adsorption properties, and reduce the reaction energy barriers.

Theoretical study of electron mobility in AlGaN back-barrier Al2O3/InAlN/GaN heterostructures under optical phonon scattering

Considering the strong built-in electric field caused by polarization in wurtzite nitride heterostructures, the energy levels and wave functions of the two-dimensional electrons in AlyGa1−yN back-barrier Al2O3/InxAl1−xN/GaN heterostructures are calculated using the finite element difference method. The dispersion relations and electrostatic potentials of optical phonons are obtained by the transfer matrix method. The electron mobility under optical phonon scattering is studied based on the theory of Lei–Ting force balance equation. The influences of AlyGa1−yN back barrier, ternary mixed crystal effect, and size effect are also analyzed by comparing with the Al2O3/InxAl1−xN/GaN heterostructure without back barrier. It is found that the introduction of a back barrier can attenuate the effect of gate-insulating layer, but enhance the effect of barrier and channel layers on electronic states. Then, the interaction between electrons and optical phonons is weakened, so the electron mobility in AlyGa1−yN back-barrier Al2O3/InxAl1−xN/GaN heterostructure is higher than that in Al2O3/InxAl1−xN/GaN structure under the same conditions. It is also found that using a thinner AlyGa1−yN film with y = 0.25 as the back-barrier layer of Al2O3/InxAl1−xN/GaN heterostructure is more conducive to improving 2DEG mobility. These conclusions can provide references for the preparation of InxAl1−xN/GaN heterojunction devices.

Constructing Interfacial Charge Transfer Channels and Electric Field in Violet Phosphorus-Based van der Waals Heterojunction for Phototherapy of Periodontitis.

Periodontitis, a chronic oral disease instigated by bacteria, severely compromises human oral health. The prevailing clinical treatment for periodontitis involves mechanical scraping in conjunction with antibiotics. Phototherapy is employed to rapidly remove the bacteria and achieve periodontitis treatment, effectively circumventing the adverse effects associated with traditional therapies. Constructing 2D/2D van der Waals (VDW) heterojunctions is a key strategy for obtaining excellent photocatalytic activity. Herein, a 2D/2D violet phosphorus (VP)/Ti3C2 VDW heterojunction is designed using an interfacial engineering strategy. By constructing an electron transport "bridge" (P-Ti bond) at the heterogeneous interface as an effective transfer channel for photogenerated carriers, a compact monolithic structure between the VP and Ti3C2 phases is formed, and the spatial barrier for electron transfer at the interface is eliminated. Meanwhile, the strong directional built-in electric field induced by the intensive electron-coupling effect at the heterogeneous interface served as an internal driving force, which greatly accelerates the exciton dissociation and charge transfer in the photocatalytic process. These excited photogenerated electrons and holes are trapped by O2 and H2O on the surfaces of Ti3C2 and VP, respectively, and are subsequently catalytically converted to antibacterial reactive oxygen species (ROS). The VP/Ti3C2 VDW heterojunction eradicated 97.5% and 98.48% of Staphylococcus aureus and Escherichia coli, respectively, by photocatalytic and photothermal effects under visible light for 10 min. The VP/Ti3C2 nanoperiodontal dressing ointment effectively attenuated inflammatory response, reduced alveolar bone resorption, and promoted periodontal soft and hard tissue repair. Its periodontitis therapeutic effect outperforms the clinically used Periocline.

Strong Second-Harmonic Generation Induced by a Triphenylamine-Based Bismuth-Organic Framework for Photocatalytic Activity Enhancement.

Taking advantage of the well-defined geometry of metal centers and highly directional metal-ligand coordination bonds, metal-organic frameworks (MOFs) have emerged as promising candidates for nonlinear optical (NLO) materials. In this work, taking a photoresponsive carboxylate triphenylamine derivative as an organic ligand, a bismuth-based MOF, Bi-NBC, NBC = 4',4‴,4‴″-nitrilotris(([1,1'-biphenyl]-4-carboxylic acid)) is obtained. Structure determination reveals that it is a potential NLO material derived from its noncentrosymmetric structure, which is finally confirmed by its rarely strong second harmonic generation (SHG) effect. Theoretical calculations reveal that the potential difference around Bi atoms is large; therefore, it leads to a strong local built-in electric field, which greatly facilitates the charge separation and transfer and finally improves the photocatalytic performance. Our results provide a reference for the exploration of MOFs with NLO properties.

Enhancing Electrochemical Signal for Efficient Chiral Recognition by Encapsulating C60 Fullerene into Chiral Lanthanum-Based MOFs.

Chiral metal-organic frameworks (MOFs) have attracted much attention due to their highly tunable regular microporous structures. However, chiral electrochemical recognition based on chiral MOFs is often limited by poor charge separation and slow charge transfer kinetics. In this case, C60 can be encapsulated into the cavity of [La(BTB)]n by virtue of host-guest interactions through π-π stacking to synthesize the chiral composite C60@[La(BTB)]n and amplify electrochemically controlled enantioselective interactions with the target enantiomers. A large electrostatic potential difference is generated in chiral C60@[La(BTB)]n due to the host-guest interaction and the inhomogeneity of the charge distribution, leading to the generation of a strong built-in electric field and thus an overall enhancement of the conductivity of the chiral material. Their enantioselective detection of tryptophan enantiomers was demonstrated by electrochemical measurement. The results showed that chiral MOF materials can be used for enantiomeric recognition. It is worth noting that this new material derived from the concept of host-guest interaction to enhance charge separation opens up unprecedented possibilities for future enantioselective recognition and separation.

Optimizing construction of fern-like Co3O4@Ni3Fe-LDH p-n heterojunction for boosting photo-assisted-electronic N2 reduction into NH3 and DFT calculation

Herein, a fern-like p-n heterojunction by anchoring Ni3Fe-LDH nanoplates onto Co3O4 nanoneedles have been optionally constructed. Essentially, p-n heterojunction ensured to induce strong built-in electric field, and inherit interfacial electron redistribution. Based on their compatible and well-matched electronic band structures, a staggered type-II photo-generated electron/holes transfer pathway have been elaborated by density functional theory calculation (DFT), in situ irradiation X-ray photoelectron spectroscopy (XPS), and fluorescent decay. This band bending and charge migrating module conferred the architecture with strong redox ability, sufficient exciton dissociation, and admirable optoelectronic characteristics. Moreover, the heterostructure acquired broad absorption spectrum to exhibit outperforming photocatalytic effect. Totally, this electron redistribution at the hierarchical interface, a type-II scheme charge-transfer pathway and the oxygen defects would lead to high efficiency in solar light assisted N2 reduction. Typically, Co@Ni3Fe-2 catalyst exhibited the highest NH3 production rate of 16.15 μg h−1 mgcat.−1 and Faraday efficiency (FE) of 31.57% at −0.6 V vs. RHE in 0.1 M Na2SO4 solution. Fortunately, with light exposure, the NH3 production rate and FE could increase by 27.9% and 18.1% than that under dark. This work would provide a plausible attitude towards the design of high efficient photocatalyst for artificial photosynthesis with multi-functionalized coupling effect.

Layer stacked polyimide with great built-in electronic field for fast lithium-ion storage based on strong p-p stacking effect

Polyimide has been regarded as a potential organic cathode for lithium-ion batteries (LIBs) due to its excellent solvent resistance, thermodynamic stability and flexibly programmable polymer structure. However, the poor conductivity, easy entanglement and agglomeration of PI chains lead to slow ion diffusion, poor electron transfer, and insufficient reaction, which make it difficult to effectively exert its theoretical capacity at high current density. Herein, a layer stacked polyimide cathode (NT-U) based on π-π stacking effect was successfully obtained. NT-U possesses a large molecular dipole moment that induced by the strong electronegative groups in PI and further enhanced by the π-π stacking structure, which contributes to the formation of a robust built-in electric field (BIEF). The strong BIEF in this highly crystalline PI plays a critical role in accelerating the charge transport dynamics and improving electrochemical performances of LIBs, as verified by in-situ XRD, ex-situ FTIR, ex-situ XPS, and ex-suit SEM, DFT calculations. These findings provide new insights into the construction of PIs cathode based on the mechanism of dipole and BIEF for fast and efficient energy storage.

Built-in electric field drives n-n heterojunction toward enhanced electrochemical freshwater and seawater oxidation

Optimizing the electron cloud density on the catalyst surface is the key to achieving fast kinetics for oxygen evolution reaction (OER). Here, a n-n Fe2P/NiCoP core/shell with strong built-in electric field (BEF) is successfully constructed to enable efficient local charge redistribution at heterointerface and contribute to extraordinary OER performance. Remarkably, the optimized Fe2P/NiCoP catalyst only requires the overpotentials of 272 and 291 mV to achieve a current density of 10 mA·cm−2 in 1 M KOH and alkaline seawater solutions, along with superb electrochemical stability over 140 h and 120 h, respectively. Detailed experimental and theoretical studies demonstrate that the well-designed BEF at the heterointerface of Fe2P/NiCoP n-n heterojunction can accelerate the charge transfer and enhance the conductivity. In addition, the self-propelled electron transfer across the n-n interface can prompt localized charge redistribution at the interface region, leading to enhanced adsorption of OH– and thus significantly boosting the kinetics of OER. This research paves a new avenue for the fabrication of heterostructured catalysts with BEF and optimized interfacial electron cloud for the enhanced OER.

Substantial Impact of Built-in Electric Field and Electrode Potential on the Alkaline Hydrogen Evolution Reaction of Ru-CoP Urchin Arrays.

Although great efforts on the delicate construction of a built-in electric field (BIEF) to modify the electronic properties of active sites have been conducted, the substantial impact of BIEF coupled with electrode potential on the electrochemical reactions has not been clearly investigated. Herein, we designed an alkaline hydrogen evolution reaction (HER) catalyst composed of heterogeneous Ru-CoP urchin arrays on carbon cloth (Ru-CoP/CC) with a strong BIEF with the guidance of density functional theory (DFT) calculations. Impressively, despite its unsatisfactory activity at 10 mA cm-2 (overpotential of 44 mV), Ru-CoP/CC exhibited better activity (357 mV) than the benchmark Pt/C catalyst (505 mV) at 1 A cm-2 . Experimental and theoretical studies revealed that strong hydrogen adsorption on the interfacial Ru atoms created a high energy barrier for hydrogen desorption and spillover, resulting in unsatisfactory activity at low current densities. However, as the electrode potential became more negative (i.e., the current density increased), the barrier for hydrogen spillover from the interfacial Ru to the Co site, which had near-zero hydrogen adsorption energy, significantly decreased, thus greatly accelerating the whole alkaline HER process. This explains why the activity of Ru-CoP is relatively susceptible to the electrode potential compared to Pt/C.

Mechanism analysis of photocatalytic activity on Semiconductor-Type-Modulated heterojunctions

The construction of heterojunction is one of the most popular strategies to improve the performance of photocatalysts, but the influence of heterojunction types on their photocatalytic behaviors is rarely investigated. Here, the p-n and n-n type heterojunctions were constructed through combining p-type BiOBr (p-BOB) or n-type BiOBr (n-BOB) with n-type g-C3N4 (CN), and their photocatalytic performances were evaluated through RhB degradation and production of H2 in comparison with that of pure n-/p- BiOBr semiconductor. The n-n type heterojunction n-BOB/CN exhibits more excellent photocatalytic performance than that of p-n type heterojunction p-BOB/CN though the latter presents more efficient separation of photogenerated carriers with the strongest photocurrent response and the smallest impedance under the driven of strong built-in electric field. The step-scheme (S-scheme) charge transfer mechanism in n-BOB/CN heterojunction was proposed based on the calculation of work functions and the corresponding valance or conduction band potential, which is responsible for the more excellent photocatalytic performance of n-BOB/CN than that of p-BOB/CN.

Semi-Coherent Heterointerface Engineering via In Situ Phase Transition for Enhanced Sodium/Lithium-Ions Storage.

To improve ion transport kinetics and electronic conductivity between the different phases in sodium/lithium-ion battery (LIB/SIB) anodes, heterointerface engineering is considered as a promising strategy due to the strong built-in electric field. However, the lattice mismatch and defects in the interphase structure can lead to large grain boundary resistance, reducing the ion transport kinetics and electronic conductivity. Herein, monometallic selenide Fe3 Se4 -Fe7 Se8 semi-coherent heterointerface embedded in 3D connected Nitrogen-doped carbon yolk-shell matrix (Fe3 Se4 -Fe7 Se8 @NC) is obtained via an in situ phase transition process. Such semi-coherent heterointerface between Fe3 Se4 and Fe7 Se8 shows the matched interfacial lattice and strong built-in electric field, resulting in the low interface impedance and fast reaction kinetics. Moreover, the yolk-shell structure is designed to confine all monometallic selenide Fe3 Se4 -Fe7 Se8 semi-coherent heterointerface nanoparticles, improving the structural stability and inhibiting the volume expansion effect. In particular, the 3D carbon bridge between multi-yolks shell structure improves the electronic conductivity and shortens the ion transport path. Therefore, the efficient reversible pseudocapacitance and electrochemical conversion reaction are enabled by the Fe3 Se4 -Fe7 Se8 @NC, leading to the high specific capacity of 439mAhg-1 for SIB and 1010mAhg-1 for LIB. This work provides a new strategy for constructing heterointerface of the anode for secondary batteries.

An Interface-cascading Silicon Photoanode with Strengthened Built-in Electric Field and Enriched Surface Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting.

To promote interfacial charge transfer process and accelerate surface water oxidation reaction kinetics for photoelectrochemical (PEC) water splitting over n-type Silicon (n-Si) based photoanodes, herein, starting with surface stabilized n-Si/CoOx , a NiOx /NiFeOOH composite overlayer was coated by atomic layer deposition and spray coating to fabricate the multilayer structured n-Si/CoOx /NiOx /NiFeOOH photoanode. Encouragingly, the obtained n-Si/CoOx /NiOx /NiFeOOH photoanode exhibits much increased PEC activity for water splitting, with onset potential cathodically shifted to ~0.96 V vs. RHE and photocurrent density increased to 22.6 mA cm-2 at 1.23 V vs. RHE for OER, as compared to n-Si/CoOx , even significantly surpassing the counterpart n-Si/CoOx /NiOx /FeOOH and n-Si/CoOx /NiOx /NiOOH photoanodes. Photophysical and electrochemical characterizations evidence that the deposited CoOx /NiOx /NiFeOOH composite overlayer would create large band bending and strong built-in electric field at the introduced cascading interfaces, thereby producing a large photovoltage of 650 mV to efficiently accelerate charge transfer from the n-Si substrate to the electrolyte for water oxidation. Furthermore, the surface oxygen vacancy enriched NiFeOOH overlayer could effectively catalyze the water oxidation reaction by thermodynamically reducing the energy barrier of rate determining step for OER.

Spaced-Confined Janus Engineering Enables Controlled Ion Transport Channels and Accelerated Kinetics for Secondary Ion Batteries.

The large grain boundary resistance between different components of the anode electrode easily leads to the low ion transport efficiency and poor electrochemical performance of lithium-/sodium-ion batteries (LIBs/SIBs). To address the issue, a Janus heterointerface with a Mott-Schottky structure is proposed to optimize the interface atomic structure, weaken interatomic resistance, and improve ion transport kinetics. Herein, Janus Co/Co2P@carbon-nanotubes@core-shell (Janus Co/Co2P@CNT-CS) refined urchin-like architecture derived from metal-organic frameworks is reported via a coating-phosphating process, where the Janus Co/Co2P heterointerface nanoparticles are confined in carbon nanotubes and a core-shell polyhedron. Such a Janus Co/Co2P heterointerface shows the strong built-in electric field, facilitating the controllable ion transport channels and the high ion transport efficiency. The Janus Co/Co2P@CNT-CS refined urchin-like architecture composed of a core-shell structure and the grafting carbon nanotubes enhances the structure stability and electronic conductivity. Benefiting from the spaced-confined Janus heterointerface engineering and synergistic effects between the core-shell structure and the grafting carbon nanotubes, the Janus Co/Co2P@CNT-CS refined urchin-like architecture demonstrates the fast ion transport rate and excellent pseudocapacitance performance for LIBs/SIBs. In this case, the Janus Co/Co2P@CNT-CS refined urchin-like architecture shows high specific capacities of 709 mA h g-1 (200 cycles) and 203 mA h g-1 (300 cycles) at a current density of 500 mA g-1 for LIBs/SIBs, respectively.

Construction of a graphitic carbon nitride-based photocatalyst with a strong built-in electric field via π–π stacking interactions boosting photocatalytic CO2 reduction

A high-efficiency photocatalyst with a strong built-in electric field was fabricated by anchoring π-conjugated molecules on the surface of crystalline nitride carbon via π–π stacking interactions with efficient photocatalytic CO2 reduction into CO and CH4.

Facilitating charge separation and migration of conjugated microporous polymers via skeleton isomerism engineering for photocatalytic reduction of uranium (VI)

Photoreduction of highly toxic and high-mobility UVI into insoluble UIV via conjugated microporous polymers (CMPs) is an effective way to extract uranium from highly acidic wastewater. Nevertheless, undesirable charge separation and migration, as well as rapid reverse charge recombination resulted in unsatisfactory photocatalytic activity of most CMPs. Herein, a pair of D-A CMPs for uranium photocatalytic reduction was developed by modulating skeleton isomerism through isomeric building blocks, named PQ-TPM (with phenanthrenequinone skeleton) and AQ-TPM (with anthraquinone skeleton). Interestingly, compared with anthraquinone skeleton CMP, phenanthrenequinone skeleton CMP can inhibit reverse charge recombination while promoting charge separation and migration due to its stronger built-in electric field and larger dipole moment. Therefore, PQ-TPM achieves an ultra-high photocatalytic UVI removal efficiency of 80.0 % within 180 min visible-light irradiation even under strongly acidic conditions (pH = 2), which was superior to AQ-TPM (30.0 %) and most reported CMPs. This study provides an unconventional concept and an emerging strategy for exploring outstanding CMPs photocatalysts for efficient processing of radionuclides.

Regulation of Bi2O3 phase structure improves the self-powered UV-blue dual‐band photoresponse of Bi2O3/TiO2 photodetectors and the imaging application

Bi2O3 semiconductors with excellent optical and electrical properties can be used in photodetectors (PDs). For different phase structures of Bi2O3 with corresponding optoelectronic properties in Bi2O3 due to differences in crystal structure and energy band structure, it is important to control the phase structure to obtain high-performance Bi2O3-based PDs. Herein, Bi2O3 nanosheet films with α and β phase structures controlled by the annealing temperature are deposited on the surface of TiO2 nanorod arrays (NRs) to construct ultraviolet (UV)-blue self-powered PDs. The effects of the energy band structure, Fermi level and carrier mobility of Bi2O3 films with different phase structures on the performance of Bi2O3/TiO2 PDs are investigated by combining theoretical calculations and experimental. The β-Bi2O3/TiO2 PDs with strong built-in electric field, large carrier mobility, small interfacial transfer resistance and long carrier lifetime exhibit excellent photoresponse characteristics. The PD demonstrates a responsivity of 26.7 mA W−1 and detectivity of 5.93 × 1011 Jones under 365 nm illumination. In addition, the imaging application of β-Bi2O3/TiO2 PD is explored by extending the photocurrent mapping values of a single PD unit to a complex array of optical information image processing in complex environments utilizing the UV-blue dual-band self-powered photoresponse properties of the PDs.

A ZnO-002/amorphous Bi2WO6 heterojunction with enhanced electron-hole separation for high-performance Cr(VI) photoreduction

The difference in bandgap structure results in better charge separation performance of crystalline/amorphous heterojunctions compared to a single component. Considering that the catalytic activity of metal oxides is often accompanied by differences in facets, it has become an interesting topic to further improve the charge separation performance of such heterojunctions by adjusting the facets at the material contact interface. This article synthesized three novels ZnO/amorphous Bi2WO6 heterojunctions with specific facets (ZnO-101/aBi2WO6, ZnO-100/aBi2WO6 and ZnO-002/aBi2WO6) by adding ZnO with different facets to bismuth tungstate precursors through hydrothermal methods. Photoelectric testing shows that compared to a single component, all three heterojunctions display efficient carrier separation characteristics. Among them, the ZnO/aBi2WO6 heterojunction with the 002 facet exhibits more excellent performance, such as photocatalytic reduction of 150 mg·L−1 Cr(VI) without hole scavenger. The system spectral and energy spectrum characterization shows that the matched band structure induces a strong built-in electric field, which accelerates the separation of bulk carriers. And meanwhile, many oxygen vacancies, high specific surface area, low interface resistance and high concentration of carriers also provide help for the treatment of pollutants. In addition, 94.49 % of the photocatalytic activity was retained after 5 cycles, which proved the excellent photo cycling stability of the heterojunction.

Ultrathin ZnO coating layer to boost the electrochemical reaction kinetics of MnO cathode for advanced aqueous zinc-ion batteries

Although conventional carbon-based materials and metallic oxide coating on manganese oxides (MnO) cathodes have been extensively researched, there are still some issues, including low electron conductivity, sluggish ions diffusion kinetics and inferior cycling stability, that need to be addressed through material modification. In this work, a simple atomic layer deposition strategy is proposed to fabricate ZnO-coated MnO (MnO@ZnO) as cathode for aqueous zinc-ion batteries. Benefiting from the heterogenous interface between ZnO and MnO, a strong built-in electric fields generated, which accelerates the electron transport and promotes a fast reaction kinetics. Additionally, the ZnO coating layer effectively alleviate the dissolution of MnO and also boost its electrical conductivity. In contrast to the pristine MnO, MnO@ZnO exhibits enhanced specific capacity of 350 mA h g−1 at 0.1 A g−1 and excellent longterm stability. In addition, the reaction mechanism is further comprehensively verified through various ex-situ characterization analyses. This work offers a simple coating method to boost electrochemical energy storage of MnO, which is of great significance for the design of cathodes with excellent performance.