ZnO Interface Research Articles

Constructing a Channel to Regulate the Electron-Transfer Behavior of CO Adsorption and Light-Driven CO Reduction by H2 over CuO-ZnO.

Photocatalytic conversions of C1 molecules under mild conditions have been widely researched in many fields. Adsorption of reactants at a catalyst surface is an indispensable process for C1 conversion and thus it might play a key role in reaction behavior. Herein, for a ZnO sample without photocatalytic activity for CO + H2 reduction, CuO is introduced into ZnO to regulate the adsorption behavior of CO on the CuO-ZnO surface and then to drive the reduction of CO by H2 under UV irradiation. The results of gas sensitivity tests and various in situ characterization methods are as expected. Specifically, surface zinc vacancies and Cu2+ sites at the interface of ZnO and CuO cooperate to construct a special electron-transfer channel (Zn-O-Cu-O) for CO adsorption [CO (ads)]. A new linear adsorption mode of CO at Cu2+ sites occurs, and this successfully changes the electron-transfer behavior of CO (ads) from donating electrons (to ZnO) to accepting electrons (from CuO-ZnO) via electron-transfer channels and d-electrons of Cu2+ matching. Then, CO molecules are reduced by H2 under UV irradiation. The strategy here provides an insight into the design of highly effective catalysts as well as an in-depth understanding of the mechanism of C1 photocatalytic conversion.

Self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on interdigitated electrodes for visible-light photodetectors

An original photodetector system based on self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on metallic interdigitated electrodes, operating as visible-light photodetector was developed by combining simple preparation approaches. Metallic interdigitated electrodes were fabricated on Si/SiO2 substrates using a conventional photolithography process. Subsequently, a Cu layer was electrodeposited on top of the metallic interdigitated electrodes. The CuO nanowire arrays (core) were obtained by thermal oxidation in air of the Cu layer. Afterwards, a ZnO thin film (shell) was deposited by RF magnetron sputtering covering the surface of the CuO nanowires. The morphological, structural, compositional, optical, electrical and photoelectrical properties of the CuO nanowire arrays and CuO–ZnO core–shell nanowire arrays grown on metallic interdigitated electrodes were investigated. The performances of the devices were evaluated by assessing the figures of merit of the photodetectors based on self-connected CuO–ZnO core–shell heterojunction nanowire arrays grown on the metallic interdigitated electrodes. The radial p–n heterojunction formed between CuO and ZnO generates a type II band alignment that favors an efficient charge separation of photogenerated electron–hole pairs at the CuO–ZnO interface, suppressing their recombination and consequently enhancing the photoresponse and the photoresponsivity of the photodetectors. The electrical connections in the fabricated photodetector devices are made without any additional complex and time-consuming lithographic step through a self-connecting approach for CuO–ZnO core–shell heterojunction nanowire arrays grown directly onto the Ti/Pt metallic interdigitated electrodes. Therefore, the present study provides an accessible path for employing low dimensional complex structures in functional optoelectronic devices such as photodetectors.

Solar-blind UV photodetector with low-dark current and high-gain based on ZnO/Au/Ga2O3 sandwich structure

High performance ultraviolet photodetectors (UV PDs) have attracted significant attention due to their great potential applications in both military and civilian fields. In this work, dual-band ultraviolet PDs with two peak responses at solar blind (255 nm) and near UV (360 nm) region were successfully fabricated by constructing ZnO/Au/Ga2O3 sandwich structure. The dark current of the ZnO/Au/Ga2O3 sandwich structure PD was reduced by 35.6 times and 5.9 times in comparison with ZnO/Au and Au/Ga2O3 MSM PDs, respectively. The responsivity of the ZnO/Au/Ga2O3 PD to 255 nm light was 336.3 A/W, which is 1443 times higher than that of the Au/Ga2O3 PD and corresponds to a gain of 1637. While, the responsivity of the ZnO/Au/Ga2O3 PD to 360 nm light was 21.6 A/W, which is only 1.2 times higher than that of the ZnO/Au PD and corresponds to a gain of 73. Based on the dependence of photocurrent on incident light intensity, the suppression of dark current in the ZnO/Au/Ga2O3 PD can be attributed to the reduction of the unsaturated bonds and the trap states at the interface of ZnO and Ga2O3. The high gain at 255 nm light in the sandwiched PD has been attributed to the migration of the photogenerated hole from Ga2O3 to ZnO and the higher electron mobility and the longer hole lifetime of ZnO than that of Ga2O3. Such ZnO/Au/Ga2O3 sandwich structure PDs with low dark current and high gain hold promise for developing high performance UVA and UVC dual-band PDs.

Cu-Ga3+-doped wurtzite ZnO interface as driving force for enhanced methanol production in co-precipitated Cu/ZnO/Ga2O3 catalysts

A detailed understanding of the interactions among the active components in gallium promoted Cu/ZnO catalysts, depending on the speciation of the gallium, are reported using in situ/operando spectroscopic studies, and their effect in the CO2 hydrogenation to methanol unraveled. In this contribution, the promoting effect of Ga3+-doped in the wurtzite ZnO lattice of a Cu/ZnO/Ga2O3 catalyst is compared to that of a zinc gallate (ZnGa2O4) phase. Remarkably, a strong inhibition of CO formation, together with an enhanced methanol formation, are observed in the Ga3+-doped ZnO sample, specifically at conditions where the competitive reverse water gas shift reaction predominates. The catalytic performance has been correlated with the microstructure of the catalyst where a surface enrichment with reduced ZnOx species, together with the stabilization of positive charged copper species and an increase in the amount of surface basic sites for CO2 adsorption are observed on the most selective sample.

Facile Fabrication of ZnO-ZnFe2O4 Hollow Nanostructure by a One-Needle Syringe Electrospinning Method for a High-Selective H2S Gas Sensor.

Herein, a facile fabrication process of ZnO-ZnFe2O4 hollow nanofibers through one-needle syringe electrospinning and the following calcination process is presented. The various compositions of the ZnO-ZnFe2O4 nanofibers are simply created by controlling the metal precursor ratios of Zn and Fe. Moreover, the different diffusion rates of the metal oxides and metal precursors generate a hollow nanostructure during calcination. The hollow structure of the ZnO-ZnFe2O4 enables an enlarged surface area and increased gas sensing sites. In addition, the interface of ZnO and ZnFe2O4 forms a p-n junction to improve gas response and to lower operation temperature. The optimized ZnO-ZnFe2O4 has shown good H2S gas sensing properties of 84.5 (S = Ra/Rg) at 10 ppm at 250 °C with excellent selectivity. This study shows the good potential of p-n junction ZnO-ZnFe2O4 on H2S detection and affords a promising sensor design for a high-performance gas sensor.

Dependence of copper particle size and interface on methanol and CO formation in CO2 hydrogenation over Cu@ZnO catalysts

The copper particle size and the interface of Cu and ZnO showed strong impacts on the formation of methanol and CO in CO2 hydrogenation over Cu@ZnO catalysts.

Highly Improved Photocatalytic Activity of Magnetically Separable Ferroferric Oxide@Zinc Oxide/Carbon Nitride Nanocomposites and Interface Mechanism

To develop an efficient and recyclable photocatalyst, ternary magnetic Fe3O4@ZnO/g-C3N4 nanocomposites were synthesized for the photodegradation of methylene blue (MB). The microstructures, magnetic response and photocatalytic activity of the as-prepared nanocomposites were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), N2 adsorption–desorption isotherms and spectrophotometer. All results indicate that ZnO nanoparticles anchor on the surface of Fe3O4 nanoparticles and Fe3O4@ZnO exists on the surface of g-C3N4 to form Fe3O4@ZnO/g-C3N4 nanocomposites. The photocatalytic activity to MB of Fe3O4@ZnO/g-C3N4 nanocomposites is significantly higher than those of pristine g-C3N4 and Fe3O4@ZnO. Owing to the heterojunctions between the interface of g-C3N4 and ZnO, the high separation efficiency of the photogenerated electrons and holes increases the radicals [Formula: see text]OH and [Formula: see text]O[Formula: see text] to photodegrade MB. Fe3O4@ZnO/g-C3N4 (20%) presents the highest MB removal of 93.74% and could be easily separated from solution with magnetic separation method.

Ultrasonic-assisted efficient degradation of tetracycline over ZnO/BiOBr heterojunctions: Synergistic effect and role of oxidative species

This research focused on synthesis of ZnO/BiOBr heterojunctions using a precipitation-hydrothermal method and their ultrasonic-assisted catalytic activity on the degradation of tetracycline. The chemical composition was detected by EDS, mapping, XPS analysis and results proved the presence of Zn, O, Bi and Br. XRD patterns and TEM images showed phase structure of both ZnO and BiOBr in ZnO/BiOBr composites, indicating the successful combination of ZnO and BiOBr. The ZnO/BiOBr heterojunctions with proper loading amount of ZnO exhibited enhanced catalytic activity compared with pure BiOBr. This enhanced ultrasonic-assisted catalytic activity could be assigned to the synergistic effect of the ultrasonic technology and the formation of heterojunction at the interface of ZnO and BiOBr. Ultrasonic irradiation generated the e−/h+charge carriers and kept the catalyst surface clean by successive surface cleaning capability. Heterojunction structure promoted the charge transfer across the interface for separating the e−/h+carriers.

Synergistic Interface and Mesopore Engineering with More and Quicker Ion Storage for Enhanced Performance of Lithium‐Ion Battery

AbstractDesigning hetero‐nanostructures is widely recognized as an effective modification strategy to obtain ZnO/Co3O4 anode materials with superior electrochemical properties. However, the lithium‐ion storage behavior of ZnO/Co3O4 has not reached a satisfied performance. Herein, based on our previous DFT results that the interface of ZnO(110)/Co3O4(220) hetero‐nanostructure possesses fast reaction kinetics because of more negative surface adsorption energy and lower diffusion barrier energy of lithium ions, we developed ZnO(110)/Co3O4(220)@C hetero‐nanostructures with both abundant interfaces and uniform mesopores structure derived from 2D MOF precursor. Especially, ZnO/Co3O4@C hybrid materials with ZnO(110)/Co3O4(220) hetero‐nanostructure show strong electronic interactions and the widen distance of the crystal plane at the interface, resulting in stable hetero‐nanostructures with faster ion diffusion channel and more active sites. Moreover, this material possesses uniform mesopores and 2D structure, which enables quicker transport capability and cycling longevity for lithium‐ion storage. Impressively, when ZnO/Co3O4@C was used as anodes in lithium‐ion batteries, the electrodes deliver improved initial specific capacities (1,630.5 and 1,496.9 mAh g−1 at 0.2 and 0.5 A g−1), excellent capacity retention (1,758.3 mAh g−1 after 370 cycles at 0.2 A g−1, and 607.7 mAh g−1 up to 650 cycles at 5 A g−1), and superior rate capacity (937 and 468 mAh g−1 at 1.0 and 5.0 A g−1 after 360 cycles).

Nitrogen-doped graphene quantum dot decorated ultra-thin ZnO nanosheets for NO2 sensing at low temperatures

Nitrogen dioxide (NO2), as a toxic gas, seriously harms the environment and human health. Semiconductor metal oxide (MOS) nanocomposites modified by N-doped graphene quantum dots (N-GQDs) have attracted extensive attention as sensing materials for NO2. Here, the N-GQDs modified ZnO composite material was successfully prepared by the hydrothermal method. Compared with pure ZnO, G-Z-2 (N-GQDS doping amount of 2 mL) exhibits excellent sensing performance for NO2. The G-Z-2 based sensor reduces the working temperature from 160 °C to 100 °C. The G-Z-2 is shown to be sensitive to 5 ppm NO2 and has a massively enhanced response of about 11.6 times. The detection limit was as low as 0.1 ppm. Moreover, it shows excellent reproducibility, selectivity and stability for the detection of NO2. The highly active N atom doping enhances the electron transfer of ZnO to N-GQDS and the adsorption of NO2 molecules. The heterojunction between ZnO and N-GQDS interface expands the resistance modulation, which improves the sensor sensitivity. This work can provide a promising strategy for improving the NO2 gas sensing performance based on semiconductor metal oxide.

Effects of substantial atomic-oxygen migration across silver − oxide interfaces during silver growth

The optimization of Ag wetting on oxides is essential to facilitate the synthesis of ultrathin Ag layers with ultralow electrical and optical losses. However, the primary challenge of increasing the Ag wetting on oxides is the strong cohesion and weak adhesion of Ag with chemically heterogeneous oxide substrates. In the present study, it was observed that the dissolution of excess atomic oxygen in ZnO lattices prior to Ag deposition induced the pronounced migration of atomic oxygen across the Ag − ZnO interface and subsequent incorporation into Ag lattices. The substantial intermixing of atomic oxygen in the Ag − ZnO matrices contributed to a decrease in the free energy at the interface, thereby weakening the driving force for the agglomeration of Ag nanoparticles during coalescence. This resulted in an increase in the adhesion and wetting of Ag geometries on the ZnO surfaces. These findings were confirmed based on the results of detailed experimental investigations in conjunction with numerical predictions. These outcomes elucidated the unconventional oxygen spillover dynamics from atomic oxygen-excess oxide surfaces. The findings obtained in the present study refute the existing convictions that the intermixing of oxygen at Ag − oxide interfaces is limited by weak charge transfer.

Fern-like metal-organic frameworks derived In2O3/ZnO nanocomposite for superior triethylamine sensing properties

Fern-like In2O3/ZnO nanocomposite with mesoporous structure was derived from MIL-68/ZIF-8 via a simple template method. Abundant nanowires grew on the surface of microrods to form novel fern-like structure. The effect of MIL-68 concentration on component, structure, morphology and gas-sensing properties of In2O3/ZnO nanocomposite were studied. The results of gas tests exhibited that the sensor based on In2O3/ZnO (the mass of MIL-68 is 0.3 g) showed excellent sensing properties to TEA, which included superior response (44.6), ultralow work temperature (100 °C) and fast response-recovery time. The enhanced gas sensing properties of fern-like In2O3/ZnO nanocomposites were due to mesoporous structure, a large specific surface area, the specific structure of abundant nanowires growing on microrods and the n-n heterojunction formed at the interface of In2O3 and ZnO, which all accelerated the gas sensing reaction between TEA molecules and adsorbed oxygen on the surface of materials. The fern-like In2O3/ZnO composite with mesoporous structure was an ideal gas sensing material for the detection of TEA.

Piezoelectric effect enhanced flexible UV photodetector based on Ga2O3/ZnO heterojunction

Piezoelectric effect has been used to modulate the transport, separation and recombination of carriers in semiconductors and consequently optimize the performance of various optoelectronic devices such as photodetectors and solar cells. In this paper, a flexible metal-semiconductor-metal (MSM) structure ultraviolet (UV) photodetector (PD) is fabricated by depositing c-axis oriented polycrystalline ZnO layer and amorphous Ga2O3 (a-Ga2O3) layer on PET substrate. The responsivity to 254 nm light can be increased 3.8 times and the response time decreases 43% by applying a tensile strain of 0.57% on the flexible detector. The improvement of the a-Ga2O3/ZnO heterojunction photodetector is explained in terms of the strain-induced modulation of the barrier height and the band offset at the Au/a-Ga2O3 interface and a-Ga2O3/ZnO interface. This work could be great value for the design and fabrication of piezoelectric effect enhanced flexible optoeletronic devices.

Effects of UV Irradiation and Storage on the Performance of Inverted Red Quantum-Dot Light-Emitting Diodes

We report the effects of ultraviolet (UV) irradiation and storage on the performance of ZnO-based inverted quantum-dot light-emitting diodes (QLEDs). The effects of UV irradiation on the electrical properties of ZnO nanoparticles (NPs) were investigated. We demonstrate that the charge balance was enhanced by improving the electron injection. The maximum external quantum efficiency (EQE) and power efficiency (PE) of QLEDs were increased by 26% and 143% after UV irradiation for 15 min. In addition, we investigated the storage stabilities of the inverted QLEDs. During the storage period, the electron current from ZnO gradually decreased, causing a reduction in the device current. However, the QLEDs demonstrated improvements in maximum EQE by 20.7% after two days of storage. Our analysis indicates that the suppression of exciton quenching at the interface of ZnO and quantum dots (QDs) during the storage period could result in the enhancement of EQE. This study provides a comprehension of the generally neglected factors, which could be conducive to the realization of high-efficiency and highly storage-stable practical applications.

Au nanoparticles/ZnO nanorods as SALDI-MS substrate for on-plate enrichment and detection of glutathione in real samples

• A SALDI-MS substrate was fabricated for on-plate selectively capturing, isolating and detecting thiols in complex samples. • The above capacities of the substrate were confirmed by detecting thiols in a mixed sample. • Glutathione in real samples was successfully detected with this substrate. As an important bio-thiol molecule, glutathione (GSH) plays key roles in various cellular activities. However, it is still a challenge to analyze GSH in complex samples because of severe signal suppression from high abundance of interferent. The most efficient approach to tackle this problem is to enrich target analytes on-plate from the complex samples by selectively capturing and isolating. Herein, the hierarchical substrates were synthesized for selective detection of GSH in real samples using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The structures are formed by homogeneously distributing Au nanoparticles (Au NPs) on ZnO nanorods (ZnO NRs). The Au NPs can selectively capture thiols through Au–S binding; ZnO NRs can not only efficiently absorb ultraviolet laser, but also isolate Au NPs–target compounds from complex samples as a carrier of Au NPs. Meanwhile, the Au–ZnO hybrid nanostructures can promote the hot electrons transfer at Au–ZnO interface and lead to higher desorption/ionization efficiency. The on-plate selective enrichment performance of the Au NPs/ZnO NRs as SALDI-MS substrates was demonstrated by successfully detecting GSH and l -Cysteine ( l -Cys) without interference peak in a mixed amino acids sample. The results in detecting GSH displayed high repeatability with relative standard deviation (RSD) of 4.91 % for substrate-to-substrate, good linearity (R 2 > 0.99), and high sensitivity with limit of detection (LOD) of 150 amol. Furthermore, the Au NPs/ZnO NRs substrate is applicable for analyzing practical samples, such as GSH in medicine and fruits, which demonstrates its potential in practical applications.

Nonconventional nucleation and growth of Au nanoparticles with improved adhesion on oxygen-excessive oxide surfaces

Controlling the number and size of nanoparticles on oxides is essential for manipulating the chemical and physical properties of Au to manifest its catalytic and sensing activities. This task requires a drastic deviation from the current understanding of the inherent nucleation behavior of Au nanoparticles weakly adhered on oxides. Herein, we report experimental and computational evidence supporting the effectiveness of incorporating excessive atomic O at ZnO surfaces on enhancing the adhesion of Au − ZnO. This result is highly contrary to current beliefs, emphasizing the advantage of O-deficient oxide surfaces for enhancing the nucleation. The use of atomic O-excessive ZnO surfaces facilitated the implementation of extremely high nucleation densities (>4 × 1012 cm−2) of Au nanoparticles, primarily with reduced diameters of 2–3 nm. These structural features were primarily attributed to the reduction in the free energy at the Au − ZnO interface due to the diffusion and participation of atomic O in Au oxidation. This result offers new insights into the crucial role played by atomic O in enhancing the adhesion of Au with oxides and the development of unique structural features of Au nanoparticles.

Preserving the Active Cu–ZnO Interface for Selective Hydrogenation of CO2 to Dimethyl Ether and Methanol

It is of importance but highly challenging for copper (Cu)-based catalysts to maintain the structure of active Cu sites under working conditions. Herein, the commercial Cu/ZnO/Al₂O₃ catalyst was confined in the mesoporous SiO₂–Al₂O₃ shell via hydrothermal synthesis (CZAS@SA) for selective hydrogenation of CO₂ to dimethyl ether (DME) and methanol. CZAS@SA catalysts exhibited higher intrinsic activity for the formation of DME and methanol and much lower intrinsic activity for CO formation than Cu/ZnO/Al₂O₃. Thus, the total selectivity of DME and methanol was enhanced from 9.1 to 63.3 mol %. In situ X-ray photoelectron spectroscopy/X-ray absorption fine structure/high-resolution transmission electron microscopy (XPS/XAFS/HRTEM) results and catalytic measurements indicated that the metallic Cu(Cu⁰)–ZnO interface was the active site for methanol formation. Commercial Cu/ZnO/Al₂O₃ underwent a separation of Cu⁰ and ZnO phases during the reaction, and this phase separation caused agglomeration of Cu⁰ and shrinking of the active Cu⁰–ZnO interface, which aggregated CO formation. The active Cu⁰–ZnO interface in CZAS@SA was preserved due to the confinement effect of the shell, which improved methanol selectivity.

Avalanche Effect and High External Quantum Efficiency in MgZnO/Au/ZnO Sandwich Structure Photodetector

AbstractThe metal–semiconductor–metal (MSM) structure is widely applied in photodetectors (PDs) owing to its simple preparation method and a more effective light collecting area. However, the realization of weak light detection remains a daunting challenge, attributed to the low external quantum efficiency (EQE) in MSM‐based PDs. Herein, sandwich structure PD (SSPD), a new structure of PD based on MSM structure, is presented to solve the problem of low gain in MSM PDs. Herein, the high‐EQE MgZnO/Au/ZnO SSPD with avalanche effect is reported for the first time. The avalanche effect is realized by changing the position of electronic transmission through energy band engineering between MgZnO and ZnO in the sandwich structure. The SSPD exhibits high EQE when photogenerated carriers get transported at the interface of ZnO and MgZnO. Under 275 nm illumination, the MgZnO/Au/ZnO SSPD achieves avalanche multiplication at 63 V and shows EQE of up to 502780% at 90 V. These results reveal that a high EQE originates from the special sandwich structure existing in MgZnO/Au/ZnO SSPD. This study presents possible guidance for high‐performance ZnO‐based avalanche PD for applications in telecommunications, sensing, and single‐photon detection.

Study of ZnO/BST interface for thin-film transistor (TFT) applications

This work presents an investigation of ZnO/BST interface for the potential use of (Ba,Sr)TiO3 as a gate–dielectric in ZnO based thin-film transistors (TFTs) for low-voltage operation. A metal-insulator-semiconductor capacitor (MIS-C) structure, which consists of a Pt/BST/ZnO stack, was fabricated on a corning glass substrate. The capacitance-voltage (C-V) characteristic of MIS-C gives the capacitance peak in both forward and backward sweep. This peak behavior of BST is due to its paraelectric nature attributed by changing the direction of a polar molecule over the applied electric field. C-V curve of ZnO/BST MIS-C structure exhibits a counter-clockwise hysteresis of -1.33 V due to the existence of donor-like oxygen vacancies present in BST and ZnO interface. The subthreshold slope of the device was found to be 203 mV/ decade and calculated using the measurement of interface state density (Dit). ZnO/BST interface also exhibits a very low value of leakage current density (3.148 × 10−7 Acm−2). Thus, the use of BST as a gate-dielectric in ZnO TFT has excellent potential, owing to its steep subthreshold slope, which implies fast switching and low off-state current.

Interfacial engineering insights of promising monolayer 2D Ti3C2 MXene anchored flake-like ZnO thin films for improved PEC water splitting

This work explores the development of novel monolayer-structured 2D Ti 3 C 2 MXene anchored flake-like ZnO thin films (Ti 3 C 2 /ZnO and ZnO/Ti 3 C 2 ) for achieving superior photoelectrochemical (PEC) water splitting activity. Specifically, swapping of Ti 3 C 2 position at the interface of ZnO strongly influenced the charge carrier generation and separation. Taking the advantage of Ti 3 C 2 MXene (electron trapping effect), Ti 3 C 2 MXene interfacially anchored on the ZnO surface (ZnO/Ti 3 C 2 ) achieved superior charge carrier separation compared to the Ti 3 C 2 developed under the ZnO (Ti 3 C 2 /ZnO). Structural studies confirmed the growth of predominant Ti 3 C 2 (002) reflection along with ZnO (002) and relative variation in the peak intensity, which revealed the role of Ti 3 C 2 position in the resultant Ti 3 C 2 /ZnO and ZnO/Ti 3 C 2 . XPS studies revealed the role of Ti 3 C 2 at the interface of ZnO. Moreover, surface morphological features demonstrated the successful interfacial interaction between monolayer Ti 3 C 2 and flake-like ZnO. Interestingly, ZnO/Ti 3 C 2 prevailed superior hydrophilic nature with water a contact angle of 42° compared to pure ZnO (85°) and Ti 3 C 2 /ZnO (56°). As a result, ZnO/Ti 3 C 2 promoted superior optical absorption with a reduced band gap of 3.10 eV. As evidenced from the above features, ZnO/Ti 3 C 2 achieved photoconversion efficiency about 0.175% at +0.6 V, which suggests the electron trapping effect of Ti 3 C 2 MXene on ZnO. In a word, swapping of Ti 3 C 2 MXene position at the interface of ZnO is an effective way to explore the electron trapping effect of Ti 3 C 2 MXene and charge carrier separation for achieving superior PEC water splitting activity. • Transformation of multilayer Ti 3 C 2 MXene into monolayer • Swapping of Ti 3 C 2 MXene position on and under the ZnO • Monolayer Ti 3 C 2 MXene interface interaction with flake-like ZnO. • Improved charge carrier separation at the interface of ZnO/Ti 3 C 2 than Ti 3 C 2 /ZnO.