Interfacial Charge Transfer Rate Research Articles

Cu2o@Cu2-Xs Core@Shell Nanocrystals: Morphologic Effect on Photocatalytic Hydrogen Production

Cu2O nanocrystals (NCs) with different morphologies, including the cube (Cub), the octahedron (Oct), and the rhombic dodecahedron (Rd) were prepared by hydrothermal synthesis by adding different kinds of anions as adsorbents. Subsequently, Cu2O NCs were used as templates to prepare Cu2O@Cu2-xS core@shell nanocomposite structures with three morphologies by the anion exchange method. By employing time-resolution photoluminescence and ultraviolet photoelectron spectroscopy, the correlations among charge carrier dynamics, energy band structure and photocatalytic activity of Cu2O@Cu2-xS was analyzed. It was found that as the Cu2-xS shell reached a certain thickness, the photocatalytic hydrogen production rates of Cub-, Oct-, and Rd-Cu2O@Cu2-xS can respectively reach 167.50, 279.18, and 111.03 μmol g-1h-1. The highest photocatalytic activity of Oct-Cu2O@Cu2-xS corresponded well to the largest interfacial charge transfer rate constant observed from time-resolution photoluminescence analysis. The apparent quantum yield of hydrogen production was further measured, showing remarkable photoactivities across the visible to near infrared region for Oct-Cu2O@Cu2-xS. The findings of this study illustrate that Cu2O@Cu2-xS NCs hold promise as practical photocatalysts for solar fuels generation.

Rational design of efficient boron-doped and nitrogen-deficient g-C3N4/lead-free Cs3Bi2Br9 perovskite nanocrystals Z-scheme heterojunction by optimised surface-active site and interfacial charge transfer

The major limitation for the photodegradation of pollutants by g-C3N4-based and lead-free halide perovskite photocatalysts are the moderate adsorption-photocatalytic ability and interfacial charge transfer rates. Herein, we have synthesized boron doped and nitrogen deficient g-C3N4 (BNCNx/y) and fabricated the BNCNx/y/Cs3Bi2Br9 heterojunctions by anti-solvent method to regulate bandgap and improve photoabsorption. The optimal ratios BNCN0.6/450/Cs3Bi2Br9 (BNCN-CBB-30) exhibited the highest degradation efficiency of 98.62 % for chloroquine phosphate (CQ) within 60 min, which possessed not only high oxidation ability (>82.19 %) for a variety of antibiotics but excellent structural stability and reusability. DFT calculations revealed that BNCNx/y/Cs3Bi2Br9 had the shortest bond distance and greater adsorption energy with CQ. Under visible light irradiation, the rapid electron transfer from Cs3Bi2Br9 to BNCN450/0.6 driven by the built-in electric field enhanced generation of •O2–, 1O2, and •OH. This work provides new insights into the internal structure design of heterojunction photocatalysts.

Research on carbon black and cerium co-doped Ti4O7-CB-Ce electrocatalytic oxidation of tetracycline-based antibiotics.

Elemental doping is a promising way for enhancing the electrocatalytic activity of metal oxides. Herein, we fabricate Ti/ Ti4O7-CB-Ce anode materials by the modification means of carbon black and cerium co-doped Ti4O7, and this shift effectively improves the interfacial charge transfer rate of Ti4O7 and •OH yield in the electrocatalytic process. Remarkably, the Ti4O7-CB-Ce anode exhibits excellent efficiency of minocycline (MNC) wastewater treatment (100% removal within 20 min), and the removal rate reduces from 100 to 98.5% after five cycles, which is comparable to BDD electrode. •OH and 1O2 are identified as the active species in the reaction. Meanwhile, it is discovered that Ti/ Ti4O7-CB-Ce anodes can effectively improve the biochemical properties of the non-biodegradable pharmaceutical wastewater (B/C values from 0.25 to 0.44) and significantly reduce the toxicity of the wastewater (luminescent bacteria inhibition rate from 100 to 26.6%). This work paves an effective strategy for designing superior metal oxides electrocatalysts.

Phosphorous Vacancy and Built-In Electric Field Effect of Co-Doped MoP@MXene Heterostructures to Tune Catalytic Activity for Efficient Overall Water Splitting.

Developing cost-effective, durable bifunctional electrocatalysts is crucial but remains challenging due to slow hydrogen/oxygen evolution reaction (HER/OER) kinetics in water electrolysis. Herein, a combined engineering strategy of phosphorous vacancy (Vp) and spontaneous built-in electric field (BIEF) is proposed to design novel highly-conductive Co-doped MoP@MXene heterostructures with phosphorous vacancy (Vp-Co-MoP@MXene). Wherein, Co doping regulates the surface electronic structure and charge re-distribution of MoP, Vp induces more defects and active sites, while BIEF accelerates the interfacial charge transfer rate between Vp-Co-MoP and MXene. Therefore, the synergistic integration of Vp-Co-MoP/MXene efficiently decreases activation energy and kinetic barrier, thus promoting its intrinsically catalytic activity and structural stability. Consequently, the Vp-Co-MoP@MXene catalyst displays low overpotentials of 102.3/196.5 and 265.0/320.0mV at 10/50mA cm-2 for HER and OER, respectively. Notably, two-electrode electrolyzers with the Vp-Co-MoP@MXene bifunctional catalysts to achieve 10/50mA cm-2, only need low-cell voltages of 1.57/1.64V in alkaline media. Besides, experimental and theoretical results confirm that the hetero-structure effectively reduces hydrogen adsorption free energy and rate-determining-step energy barrier of OER intermediates, thereby greatly boosting its intrinsically catalytic activity. This work verifies an effective strategy to fabricate efficient non-precious bifunctional electro-catalysts for water splitting via combination engineering of phosphorous vacancy, cation doping, and BIEF.

Measurement of interfacial charge transfer rate during visible light CO2 reduction under bias voltage conditions

The study of photogenerated electron transfer pathway and time scale in photoelectrocatalysis is the key factor to improve the efficiency of light energy utilization. At present, the reduction of CO2 by visible light is one of the hotspots of research, but it is difficult to determine the reduction reaction and mechanism. Therefore, we use electrochemical in situ growth technology to prepare Bi2(MoO4)3, and then use photoelectrocatalytic method to reduce CO2. The results show that the rate of charge transfer at the interface is about 10−18 cm4/s in the reduction of CO2 by visible light under bias voltage, and the catalyst can react stably for 10 h. This provides a way to optimize the photogenerated electron transfer model and to design the catalysts for the reduction of carbon dioxide under visible light.

Interconversion of sp-hybridized chemical bonds induces piezoelectric enhanced photocatalysis

The synergism of piezoelectric catalysis and plasmonic photocatalysis is an effective approach for enhancing the catalytic performance. Nevertheless, challenges remain in addressing the slow interfacial charge transfer rate and the high recombination of energetic hot electrons. In this study, we constructed a heterostructure comprising barium titanate/graphdiyne/gold nanofibers (BTO/GDY/Au NFs). The incorporation of a graphdiyne (GDY) layer serves as an electron sponge, significantly boosting the piezo-photocatalytic activity, with a degradation rate constant 3.3-fold higher than that of BTO/Au. Theoretical calculations indicated that BTO could undergo elastic deformation under ultrasound irradiation, resulting in the stretching and compression of GDY within a lattice constant range of 7.1–10.4 Å. This deformation induced the reversible conversion of sp-hybridized CC to CC, releasing electrons that could recombine with hot holes generated by the Au nanoparticles (Au NPs). Consequently, more hot electrons were able to participate in the catalytic reaction process. Furthermore, BTO/GDY/Au NFs demonstrated excellent catalytic performance in the rapid degradation of organic dyes and antibiotics in wastewater, while also inhibiting bacterial propagation. The above-mentioned results validated the feasibility of this heterostructure for practical applications. Overall, this study presents a novel piezo-photocatalysts, where the interconversion of sp-hybridized chemical bonds in GDY can serve as electron donor, thus significantly enhancing piezo-photocatalysis.

Porous hybrid encapsulation enables high-rate lithium storage for a micron-sized SiO anode.

Establishing a durable interfacial layer between an electrode and electrolyte to enable micron-sized silicon-based lithium-ion battery (LIB) anodes to achieve superior electrochemical performance is highly desired. Recent studies have shown that heterogeneous encapsulation with enhanced ion/electron transport is an effective strategy. However, the structural design of the existing hetero-coated interface lacks a reasonable ion/electron transport channel, resulting in high interfacial impedance. Herein, we designed a heterogenous MXene-mesoporous polypyrrole (mPPy) encapsulation layer onto micron-sized SiO particles. The MXene coating layer functions as a bridging interface that can build a strong chemical link to internal SiO via covalent bonding, thus reinforcing interfacial charge transfer rate. Meanwhile, it forms a dynamic connection with the outer mPPy through hydrogen bonding, which contributes to high interfacial Li+ concentration and ion/electron coupling transport rate. Accordingly, the as-prepared SiO@MXene@mPPy anode delivers a boosted specific capacity of 673.9 mA h g-1 at 2 A g-1 after 1000 cycles and high-rate capability of 777.4 mA h g-1 at 5 A g-1. Further, electrochemical kinetic analysis indicates that the MXene@mPPy coating layer shows a pseudocapacitance controlled Li storage mechanism, thereby displaying improved high-rate capability. This porous hybrid encapsulation strategy offers new possibilities for a micron-sized SiO anode to achieve an excellent performance.

Linking the Photoinduced Surface Potential Difference to Interfacial Charge Transfer in Photoelectrocatalytic Water Oxidation.

Charge transfer at the semiconductor/solution interface is fundamental to photoelectrocatalytic water splitting. Although insights into charge transfer in the electrocatalytic process can be gained from the phenomenological Butler-Volmer theory, there is limited understanding of interfacial charge transfer in the photoelectrocatalytic process, which involves intricate effects of light, bias, and catalysis. Here, using operando surface potential measurements, we decouple the charge transfer and surface reaction processes and find that the surface reaction enhances the photovoltage via a reaction-related photoinduced charge transfer regime as demonstrated on a SrTiO3 photoanode. We show that the reaction-related charge transfer induces a change in the surface potential that is linearly correlated to the interfacial charge transfer rate of water oxidation. The linear behavior is independent of the applied bias and light intensity and reveals a general rule for interfacial transfer of photogenerated minority carriers. We anticipate the linear rule to be a phenomenological theory for describing interfacial charge transfer in photoelectrocatalysis.

Enhanced photocatalytic activity of Ag/ZnO@ZIF-C with core-shell structure and multiple catalytic sites

Metal-organic frameworks (MOFs) are with extensive attention for environmental remediation due to their various modification and high density of active sites. Herein, a series of Ag/ZnO@ZIF-C with core-shell structure and graphene carbon (C) acts as a sandwich bridge were designed as a photocatalyst, accelerating the interfacial charge transfer rate between Ag and ZnO. Photocatalytic activities of Ag/ZnO@ZIF-C is remarkably improved toward rhodamine B (RhB) under UV irradiation, i.e., the degradation rate by Ag/ZnO@ZIF-C (20 wt%) is 2.27 times than that of P25. RhB molecules were simultaneously photodegraded at multiple sites, including N-site de-ethyl, conjugate structure and benzene ring. The photocatalytic upgrading performance was recognized to the synergetic interface between ZnO@ZIF-C and Ag nanoparticles (NPs) with effective separation and suppressed the recombination of electrons and holes. It is suggesting that the electrons in the valence band (VB) of ZnO are excited to the conduction band (CB) and transferred to Ag NPs through the ZIF-C layer, then react with adsorbed oxygen to create superoxide radicals and degrade RhB into small molecules. After a five-consecutive operation, its photocatalytic efficiency by Ag/ZnO@ZIF-C (20 wt%) still maintains at 95.11 %. This work provides a promising method for the rational design of high-performance carbon doped photocatalysts for environmental remediation.

Surface engineering of Ba-doped TiO2 nanorods by Bi2O3 passivation and (NiFe)OOH Co-catalyst layers for efficient and stable solar water oxidation

The rational design of heterostructures as an ideal photoelectrode system for H2 and O2 conversion in photoelectrochemical (PEC) system has been regarded as an essential key to boost PEC performance. In this work, to demonstrate the energetic photoanode cell, deposition of a thin layer of Bi2O3 is utilized to hybridize with the 5 wt% Ba-doped TiO2 nanorod heterostructure under the cascading band diagram, where Ba-doping can enhance the charge transport/separation rate in bulk phase, in terms of increasing the donor density, enhancing the bulk electronic conductivity, and increasing the band bending. Furthermore, with optimizing the thickness (∼15 nm) of Bi2O3, the (NiFe)OOH as a cocatalyst was adapted to improve the interfacial charge transfer rate in the PEC cell, reaching the high photocurrent density (J) of ∼4.1 mA/cm2 at 1.23 V (vs. Reversible Hydrogen Electrode) and stability retention of 100%, even after 15 h at 1 M NaOH under 1 Sun illumination condition. The improvement mainly comes from the extended absorption of visible light from the thin Bi2O3 layer, effective transfer/separation of photogenerated charge carriers, and acceleration of water oxidizing reaction, caused by the narrowed band gap and the favorable charge transfer under the cascading band alignment built by the heterojunction, as well as electrocatalyst, offering the timely consumption of photogenerated holes accumulated at the electrode surface.

Design and construction of a novel hierarchical Ag/{1 1 1}Ag3PO4/PANI/Pt photoanode with boosted interfacial charge transfer rate and high photocurrent density > 16 mA/cm2 for sunlight-driven water splitting

In this work, a novel hierarchical photoanode structure of Ag/{111}Ag3PO4/PANI/Pt was synthesized, demonstrating a novel and facile approach to design a high-performing Ag3PO4-based photoanode for visible-light-driven solar green hydrogen (H2) generation. The Ag3PO4 photoanode with carefully curated active facets, Ag/{111}Ag3PO4, was interfaced with a conductive polyaniline (PANI) thin film and surface decorated with platinum nanoparticles (Pt NPs) to realise the combined advantages of integrating both PANI and Pt NPs as a hole-transporting layer and co-catalysts, respectively. This novel photoanode achieved a record photocurrent density of 16.34 mA/cm2 at 1.4 V vs Ag/AgCl under AM 1.5 G solar irradiation (100 mW/cm2), which outperformed that of the bare Ag/{111}Ag3PO4 photoanode and is also the highest photocurrent density reported to date for Ag3PO4-based photoanodes. The PEC enhancement is attributed to the new exploitation of the PANI-{111}Ag3PO4p-n heterojunction, the hole-transporting property of PANI and the electron-capturing capability of Pt NPs, in which their synergetic interactions effectively led to improved light absorption, enhanced charge separation and reduced charge recombination. It is foreseen that this current work can provide a base for further nanoarchitectural design strategies to construct efficient photoanodes used in PEC water splitting application.

Modeling the Photostability of Solar Water-Splitting Devices and Stabilization Strategies.

The practical implementation of photoelectrochemical devices for hydrogen generation is limited by their short lifetimes. Understanding the factors affecting the stability of the heterogeneous photoelectrodes is required to formulate degradation mitigation strategies. We developed a multiscale and multiphysics model to investigate and quantify the photostability of photoelectrodes. The model considers the photophysical processes in an electrocatalyst-coated semiconductor immersed in electrolyte, and the kinetics of the competing water-splitting and photocorrosion reactions. When applied to 12 promising compound semiconductors for use as photoanodes (GaAs, GaP, InP, GaN, SiC, AlP, AlAs, CdTe, CdS, CdSe, ZnS, and ZnSe), the semiconductor-electrocatalyst interfacial charge transfer rate constant was found to be the most significant parameter for stabilizing the photoelectrodes. Its increase induced a sigmoid-like increase in photostability, and its optimization made it possible to stabilize nine semiconductors. The semiconductor surface back-bond energy also increased the photostability in a sigmoid-like response, and its optimization allowed to stabilize five semiconductors. The increase of irradiance induced a logarithmic drop in photostability, and limiting it to 100 W/m2 could stabilize three semiconductors. We further observed that the photostability in a device of centimeter-scale can vary by more than 50%, showing stable zones and photocorrosion hotspots. The photoelectrode's length as well as the electrocatalyst and electrolyte conductivities were found to be relevant parameters to impact this heterogeneity in the photostability. Thus, the photostability is not only defined by material properties but also by the specific combination of materials and by the device architecture. The model presented in this study can also be applied to photocathodes and other PEC designs, and can serve as a design tool for understanding, quantifying, and improving the stability.

Improving the Performance of Photocatalytic Hydrogen Production through Adjusting the Size of Defective Quantum Dots Co‐Catalyst Affected by Intramolecular Steric Hindrance on Thermal Stability of Functional Groups

Quantum dots (QDs) co‐catalysts have been extensively studied in the field of photocatalytic hydrogen production (PHP) due to their limited domain effect. However, how to adjust the size of QDs co‐catalysts remains a big challenge. Herein, Ni2P QDs co‐catalysts are synthesized via phosphating metal–organic frameworks (MOFs). Due to the intramolecular steric hindrance on the thermal stability of functional groups: electron‐giving functional groups ‐NH2, ‐OH, and electron‐absorbing functional group ‐COOH, the electronic symmetry of organic ligands and the coordination with metal ions is affected, resulting in three sizes of Ni2P QDs co‐catalysts in the phosphating process, and the smallest one has the highest interfacial charge injection efficiency and transfer rate. Meanwhile, the carbon defects of the carbon skeleton produced in the phosphating process, in which the band position is lower than the conduction band of the Zn0.5Cd0.5S (ZCS) catalyst, can effectively collect electrons and inhibit the recombination of photocarriers to a greater extent, and Ni defects adjust the internal electronic structure of Ni2P QDs. The results of experiments and density functional theory calculations demonstrate that Ni2P@ZCS has excellent electronic structure and electron transfer efficiency. Thus, the best PHP performance of Schottky junctions Ni2P@ZCS is achieved with the combined efforts of QDs co‐catalysts and defects.

Lattice-matched in-situ construction of 2D/2D T-SrTiO3/CsPbBr3 heterostructure for efficient photocatalysis of CO2 reduction

The elaborate regulation of heterostructure interface to accelerate the interfacial charge separation is one of practicable approaches to improve the photocatalytic CO2 reduction performance of halide perovskite (HP) materials. Herein, we report an in-situ growth strategy for the construction of 2D CsPbBr3 based heterostructure with perovskite oxide (SrTiO3) nanosheet as substrate (CsPbBr3/SrTiO3). Lattice matching and matchable energy band structures between CsPbBr3 and SrTiO3 endow CsPbBr3/SrTiO3 heterostructure with an efficient interfacial charge separation. Moreover, the interfacial charge transfer rate can be further accelerated by etching SrTiO3 with NH4F to form flat surface capped with Ti−O bonds. The resultant 2D/2D T-SrTiO3/CsPbBr3 heterostructure exhibits an impressive photocatalytic activity for CO2 conversion with a CO yield of 120.2 ± 4.9 µmol g−1 h−1 at the light intensity of 100 mW/cm2 and water as electron source, which is about 10 and 7 times higher than those of the pristine SrTiO3 and CsPbBr3 nanosheets, surpassing the reported halide perovskite-based photocatalysts under the same conditions.

Effect of mixed-phase TiO2 doped with Ca2+ on charge transfer at the TiO2/graphene interface

Conductive coatings can effectively prevent fires and explosions caused by electrostatic sparks, ensuring safety in production and life. However, the commonly used TiO2 has poor electrical conductivity. Herein, we employ mixed-phase TiO2 based on Ca/TiO2/graphene and dope Ca2+ into the TiO2 lattice. The results show that the Ca2+-doped mixed-phase TiO2/graphene composite (T-G-Ca) has excellent electrical conductivity with a minimum resistivity of 0.082 Ω cm, which is 7 times higher than the electrical conductivity of single-crystal Ca/TiO2/graphene (0.58 Ω cm). The improved electrical conductivity is attributed to the easier electron-hole separation of mixed-phase TiO2 than single-crystal TiO2, especially the synergistic effect with Ca2+ that significantly increases the carrier concentration. Meanwhile, a new three-dimensional conductive path (Ca-O-C) is formed between graphene and Ca2+-doped mixed-phase TiO2, which effectively increases the interfacial charge transfer rate. It is the significant enhancement of both carrier concentration and charge transfer that leads to a significant decrease in resistivity. Therefore, T-G-Ca has potential applications in the field of conductive coatings.

Nanoflower shaped NiO/CeO2 p-n junction material for the degradation of pollutant under visible light

The potential need of p–n junctions create an optimistic way of supporting photogenerated electron–hole pair separation and improving interfacial charge-transfer rates. In this context, a p-type semiconductor NiO can couple with n-type CeO2, thus approving visible light activity by forming p-n junctions. The visible light activity of two large band gap semiconductors still lacks some significant reasons. To solve this, for the first time, this paper reports 3D flower shaped p − n heterojunction NiO/CeO2 synthesized via thermal decomposition method and studied their properties through various instrumental techniques. Besides, the photocatalytic mechanism of p − n junction and the degrading efficiency of organic pollutant methyl orange (MO) for the synthesized catalysts was discussed. This achieves the outstanding activity and showed better stability which are useful for future applications.

Insights into the electrooxidation of florfenicol by a highly active La-doped Ti4O7 anode

In this study, a novel active La-doped Ti4O7 (La-Ti4O7) electrode was fabricated through a simple one-step spark plasma sintering method. Characterization results revealed that La was successfully incorporated into the crystal lattice of Ti4O7, leading to an increase in the surface oxygen vacancy content (from 26% to 31%), oxygen evolution potential (from 2.24 to 2.75 V vs SCE), hydroxyl radical yield [•OH, from 0.123 to 0.205 μmol/(min·cm2)] and interfacial charge-transfer rate compared to pristine Ti4O7. La-Ti4O7 electrodes achieved efficient anodic oxidation of florfenicol (FLO, one of the most widely used antibiotics), which mainly due to the indirect oxidation mediated by electro-generated •OH. The degradation of FLO by La-Ti4O7 electrodes fitted well with the pseudo-first-order kinetic model, and the optimal degradation rate constant (kFLO, 0.021 min−1) was achieved by 1.60% La-Ti4O7 electrode. In addition, the degradation efficiency of FLO increased with the increasing current density, decreasing pH and co-existing Cl-, while an opposite pattern was observed with co-existing NO3–. Seven degradation products of FLO were identified by UPLC-MS/MS. The main degradation pathways included hydrolysis, hydroxylation, dechlorination and C-N bonds cleavage. The energy consumption (EC) for FLO degradation ranged from 1.91 to 29.53 Wh/L, and the optimal practical conditions were obtained by the analysis of the calculated ratios of kFLO and EC. Moreover, La-Ti4O7 electrode maintained excellent removal efficiency of FLO (>93.5%) within 20 degradation cycles. This study suggested that La-Ti4O7 is a promising anodic material for the efficient treatment of FLO-polluted water.

Direct observation of carrier accumulation at the PbSe colloidal quantum Dot/ZnO interface

For the first time, we quantified the ZnO/lead sulfide (PbSe) contact resistance directly using a ZnO/PbSe/ZnO test platform, eliminating the additional interface associated with metal electrodes which complicate the direct analysis of the contact properties. We demonstrated that a significant enhancement of the interfacial charge transfer rate through the ligand removal process of the PbSe colloid quantum dots (CQDs) with ammonium sulfide ((NH4)2S) treatment results from the accumulation of mobile carriers. The ligand removal process dramatically decreased the contact resistivity from 1.0ⅹ103 (after 1,2-ethanedithiol (EDT)-treatment) to 7.9 Ω cm2. A significant increase in the carrier concentration was observed in the ZnO/PbSe contact region as well as the PbSe CQD channel, mitigating carrier depletion at the contact. We propose that the ligand removal process led to thermally-activated hopping of carriers from the ZnO to the PbSe instead of trap-assisted tunneling in the EDT-treated PbSe CQDs.

Transparent Ultramicroelectrodes for Studying Interfacial Charge-Transfer Kinetics of Photoelectrochemical Water Oxidation at TiO2 Nanorods with Scanning Electrochemical Microscopy

Scanning electrochemical microscopy (SECM) has been extensively applied to the electrochemical analysis of the surfaces and interfaces of a photoelectrochemical (PEC) system. A semiconductor photoelectrode with a well-defined geometry and active surface area comparable to SECM's tip is highly desired for accurately quantifying interfacial charge-transfer activities and photoelectrochemically generated redox species, where the broadening effects due to the mass transfer gradient and nonlocal electron transfer at a planar semiconductor surface can be minimized. Here, we present a newly developed platform as a SECM substrate for investigating semiconductor PEC activities, which is based on a transparent ultramicroelectrode (UME) fabricated by using two-step photolithographic patterning and ion milling methods. This transparent UME with a 25 μm recessed disk shape is fully characterized with SECM for quantifying the interfacial charge-transfer rates of IrCl62-/IrCl63- by comparing with theoretical results from finite element simulations in COMSOL Multiphysics. When coated with TiO2 nanorods as a model semiconductor material, the transparent UME can be used to quantify the catalytic PEC water oxidation in a feedback mode of SECM by sampling tip and substrate current signals simultaneously. This transparent UME-SECM study provides insights into the potential-dependent PEC water oxidation reaction mechanism and the quantitative analysis of photocurrent contributions from water oxidation and the SECM tip-generated redox mediator. The transparent UME-SECM method can be potentially expanded to other SECM operation modes such as surface interrogation for understanding the dynamics of the electrode surfaces and interfaces of a PEC system.

Boosting the Rate Performance of Li–S Batteries via Highly Dispersed Cobalt Nanoparticles Embedded into Nitrogen-Doped Hierarchical Porous Carbon

Boosting the Rate Performance of Li–S Batteries via Highly Dispersed Cobalt Nanoparticles Embedded into Nitrogen-Doped Hierarchical Porous Carbon