Surface Electronic Properties Research Articles

Progress Made in Non-Metallic-Doped Materials for Electrocatalytic Reduction in Ammonia Production

The electrocatalytic production of ammonia has garnered considerable interest as a potentially sustainable technology for ammonia synthesis. Recently, non-metallic-doped materials have emerged as promising electrochemical catalysts for this purpose. This paper presents a comprehensive review of the latest research on non-metallic-doped materials for electrocatalytic ammonia production. Researchers have engineered a variety of materials, doped with non-metals such as nitrogen (N), boron (B), phosphorus (P), and sulfur (S), into different forms and structures to enhance their electrocatalytic activity and selectivity. A comparison among different non-metallic dopants reveals their distinct effects on the electrocatalytic performance for ammonia production. For instance, N-doping has shown enhanced activity owing to the introduction of nitrogen vacancies (NVs) and improved charge transfer kinetics. B-doping has demonstrated improved selectivity and stability, which is attributed to the formation of active sites and the suppression of competing reactions. P-doping has exhibited increased ammonia generation rates and Faradaic efficiencies, likely due to the modification of the electronic structure and surface properties. S-doping has shown potential for enhancing electrocatalytic performance, although further investigations are needed to elucidate the underlying mechanisms. These comparisons provide valuable insights for researchers to conduct in-depth studies focusing on specific non-metallic dopants, exploring their unique properties, and optimizing their performance for electrocatalytic ammonia production. However, we consider it a priority to provide insight into the recent progress made in non-metal-doped materials and their potential for enabling long-term and efficient electrochemical ammonia production. Additionally, this paper discusses the synthetic procedures used to produce non-metal-doped materials and highlights the advantages and disadvantages of each method. It also provides an in-depth analysis of the electrochemical performance of these materials, including their Faradaic efficiencies, ammonia yield rate, and selectivity. It examines the challenges and prospects of developing non-metallic-doped materials for electrocatalytic ammonia production and suggests future research directions.

Electronic Band Structure and Fermi Surface Analysis of Ce2 Ni1-Xcoxge2: A Pseudo Potential Study

This study uses pseudopotential calculations to investigate the electronic band structure and Fermi surface properties of Ce2Ni1-xCoxGe2 alloys. The research problem centers on understanding the effects of Co substitution on the electronic properties of these alloys, particularly regarding potential high-temperature superconducting behavior. The methodology involves density of states (DOS) analysis and Fermi surface calculations for Ce2Ni1-xCoxGe2 alloys with varying Co concentrations. Results reveal a notable increase in DOS around the Fermi level with increasing Co substitution, indicative of enhanced metallic behavior and potential superconducting characteristics. Additionally, band structure analyses demonstrate the significant role of hybridization between Ce 4f, Ni/Co 3d, and Ge 4s/4p orbitals in determining electronic behavior. Fermi surface calculations unveil a transition from near-spherical to complex 2D and 3D shapes with higher Co concentrations, suggesting modifications in Fermi energy surface nestings or electron scattering. This study's conclusions emphasized the intricate electronic structure of Ce2Ni1-xCoxGe2 alloys and highlighted the potential for further exploration in high-temperature super conductivity research.

Enhanced Supercapacitive Performance in Catalyst‐Free Binary Composite SnO2–RuO2 Nanostructured Thin Films for Symmetric Supercapacitor Device

In the present work, thin film electrodes of ruthenium oxide (RuO2), tin oxide (SnO2), and their composite SnO2–RuO2 are deposited on 304 stainless steel substrates using pulsed laser deposition (PLD). These nanostructured electrodes are then evaluated for their suitability in electrochemical energy storage applications. A symmetric supercapacitor device (SSD) is constructed using the SnO2–RuO2 composite electrodes. Compared to individual SnO2 and RuO2 electrodes, the composite electrodes exhibit enhanced specific capacitance and cycle life. This improvement is attributed to modifications in surface morphology and electronic properties. This modified surface morphology of the composite electrode, creates favourable conditions for electrolyte interaction and ion transport, ultimately contributing to the observed increase in specific capacitance. Specifically, the composite electrode demonstrates a specific capacitance of 170.2 Fg−1 at a current density of 0.1 mA cm−2, outperforming SnO2 (37.4 Fg−1). The SnO2–RuO2//SnO2–RuO2 SSD exhibites a specific capacitance of 70.0 Fg−1 at a current density of 0.1 mA cm−2, coupled with energy density and power density values of 19.05 Wh kg−1 and 645 W kg−1, respectively, within a voltage window of 1.4 V. The SSD displays an impressive capacitive retention of 81.27% over 10 000 cycles, indicating its potential for practical energy storage applications.

Structural behavior and surface layer modification of (E)-N'-((1H-indol-3-yl) methylene)-4-chlorobenzohydrazide: Spectroscopic, DFT, biomedical activity and molecular dynamic simulation against Candida Albicans receptor

The synthesis of (E)-N'-((1H-indol-3-yl) methylene)-4-chlorobenzohydrazide (IMCBH) (A2) was achieved by reacting indole-3-carboxyaldehyde with 4-chlorobenzohydrazide. Their different biological properties, including antibacterial and antifungal activities, were assessed. The synthesized heterocyclic compound was characterized by its TLC, melting point, FT-IR, 1H, and 13C NMR spectral studies. Biological studies were considered to predict the effect of ligand-DNA complexed behavior. The computational methods induce an important impact to on understanding the molecular and electronic behavior of spectrum heterocyclic compounds. Using the more widely used DFT methods, the structural and electronic behavior of the synthesized IMCBH were computed. Quantum chemical reactivity parameters were calculated to reveal the active site's behavior towards other electronic-system variety. TD-DFT level was performed to depict the UV–vis and ECD spectra. Further studies were performed on the designed organic layer of the tested compound, such as electronic band structure and DOS to investigate the surface electronic properties in charge distribution. Also, Forcite dynamics on the organic surface were considered to predict the stability of the proposed solid layer. Regarding the antibacterial activity, IMCBH was docked against 6KWT target protein aiming to antibacterial effect comparison relating to co-crystalized control. Molecular dynamic simulation was performed to investigate the degree of docked pose stability according to crucial RMSD, RMSF, and H-bonds parameters.

Ligand modulation of active center to promote lead-free Cs2AgInCl6 photocatalytic CO2 reduction

Metal halide perovskites (MHP) are potential candidates for the photocatalytic reduction of CO2 due to their long photogenerated carrier lifetime and charge diffusion length. However, the conventional long-chain ligand impedes the adsorption and activation of CO2 molecules in practical applications. Here, a ligand modulation technology is employed to enhance the photocatalytic CO2 reduction activity of lead-free Cs2AgInCl6 microcrystals (MCs). The Cs2AgInCl6 MCs passivated by Oleic acid (OLA) and Octanoic acid (OCA) are used for photocatalytic CO2 reduction. The results show that the surface defects and electronic properties of Cs2AgInCl6 MCs can be adjusted through ligand modulation. Compared with the OLA-Cs2AgInCl6, the OCA-Cs2AgInCl6 catalyst demonstrated a significant improvement in the catalytic yield of CO and CH4. The CO and CH4 catalytic yields of OCA-Cs2AgInCl6 reached 171.88 and 34.15 µmol g−1 h−1 which were 2.03 and 12.98 times higher than those of OLA- Cs2AgInCl6, and the total electron consumption rate of OCA-Cs2AgInCl6 was 615.2 µmol g−1 h−1 which was 3.25 times higher than that of OLA-Cs2AgInCl6. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra revealed the enhancement of photocatalytic activity in Cs2AgInCl6 MCs induced by ligand modulation. This study illustrates the potential of lead-free Cs2AgInCl6 MCs for efficient photocatalytic CO2 reduction and provides a ligand modulation strategy for the active promotion of MHP photocatalysts.

Investigation of surface morphology, optical and electronic properties of Mg2Si thin films on Si(111)

Investigation of surface morphology, optical and electronic properties of Mg2Si thin films on Si(111)

Emergence of enhanced photocatalytic response in GO-hBN nanocomposites with tuned non-linear optical and surface electronic properties

The hexagonal Boron Nitride (hBN) nanostructures with tuned physicochemical properties find huge applications in optoelectronic devices. Herein, we have synthesized nanocomposite of hBN with graphene oxide (GO) in various ratios to acquire composition-dependent variation in their structural, surface electronic, linear, and non-linear optical properties. The insertion of GO in hBN nanosheets has modified their strain landscape, the electronic charge transfers from GO to hBN, increased the working time of free charge carriers, and suppressed electron-hole recombination, thus modifying its work function (WF). GO-hBN nanocomposites observed to have reduced bandgap where creation of defect induced mid-gap states lead to enhancement in non-linear absorption of two photons. Herein, we have established a linear relationship between Urbach energy (Eu), a measure of disorders and non-linear absorption coefficient (αNL). Additionally, we have observed that the tuned bandgap of the nanocomposites has significantly enhanced their performance as high-performance photocatalysts for the degradation of methyl orange, compared to bare hBN or GO. As a result, we discovered that Eu, αNL, WF and photodegradation activity of GO-hBN nanocomposites exhibit analogous variations in response to changes in the content of GO. Thus, by strategically prioritizing the modification of a single parameter while considering the potential effects on other relevant properties for application purpose, GO-hBN can effectively harness large spectrum areas for catalytic and optoelectronic applications.

Confined and spontaneously transformed oxidation structures due to the intrinsic heterogeneous surface morphology of C3N monolayer.

Identifying the oxidation structure of two-dimensional interfaces is crucial to improve surface chemistry and electronic properties. Beyond graphene with only phenyl rings, a novel carbon-nitrogen material, C3N, presents an intrinsic heterogeneous surface morphology where each phenyl ring is encircled by six nitrogen atoms, yet its atomistic oxidation structure remains unclear. Here, combining a series of density functional theory calculations and abinitio molecular dynamics simulations, we demonstrate that thermodynamically favorable oxidation loci are confined to the phenyl ring, and kinetic transformations of oxidation structures are feasible along the phenyl ring, whereas those toward nitrogen atoms are proven to be extremely difficult. These results are attributed to the lower barrier of oxygen atom migration along the phenyl ring, while the significantly high barriers toward nitrogen atoms are due to the heterogeneous potential energy surface for oxygen-C3N interaction. This work highlights the significance of surface morphology on the characteristics of oxidation structure, offering insights into tunable electronic properties via confined interfacial oxidation.

Tin oxide thin films on Ag(111): Thickness and temperature dependent study of surface structure and electronic properties

Growth and structure of tin oxide films on Ag(111) from submonolayer to 10 monolayer equivalent thickness have been studied using low energy electron diffraction (LEED), x-ray photoemission spectroscopy (XPS) and angle-resolved photoemission spectroscopy techniques for room temperature (RT) and high temperature (HT) (573 K). For RT growth, most of the tin is oxidised to form tin oxide (SnOx) as confirmed by XPS where no metallic component is noticed. However, the grown films are not epitaxial or ordered which can be confirmed by no spots in LEED for higher coverage. Metallic Sn along with two oxidation states of Sn are noticed for HT growth, with the surface mainly composed of SnO2. LEED pattern shows the presence of c(2 × 2) and (3 × 1) along with two different hexagonal multidomain type patterns. The electronic structure for lower coverage resembled the Sn/Ag(111) alloy structures for lower coverage. For higher coverages appearance of three bands below 2 eV binding energy was noticed.

ZSM-5@MOF-199 core-shell composite adsorbent: Rapid ambient synthesis and CO/CO2 adsorption

Using a hydroxy double salt intermediate, we demonstrated rapid room temperature fabrication of ZSM-5@MOF-199 core–shell sorbents. Copper chloride was compatible with the ZnO-assisted MOF growth scheme. The structural and chemical properties of the composite were fine-tuned through either the core or the shell modification, targeting a superior adsorption capacity for CO and CO2 compared to parent adsorbents. For example, the Na2S2O3-assisted MOF-199 shell reduction enriched surface Cu+ and enhanced CO adsorption capacity. Modulating the zeolite core to protonic hierarchical ZSM-5 (HZSM-5) increased CO and CO2 uptake by 20 % and 28 %, respectively. The isosteric heat of adsorption revealed that the HZSM-5 core altered surface electronic properties and influenced the CO2 adsorption performance. Thermodynamic analysis indicated that the adsorption processes involved a combination of physisorption and electrostatic interactions with an ordered arrangement of adsorbates. The core–shell sorbent can be easily tuned for selective separation of CO and CO2.

A carbon-promoted galvanic replacement method to synthesize efficient PdNi nanoalloy catalyst

PdNi nanoalloy catalysts were prepared by a carbon-promoted galvanic replacement method. Characterizations and control experiments show the increased replacement rate of metal Ni with Pd2+ ion can be attributed to the higher electrode potential and smaller crystalline sizes caused by carbon doping. Introduction of carbon (C) into Ni particles not only accelerates the formation process of PdNi nanoalloys, but also enables C atoms to successfully enter the lattice interstices of PdNi nanoalloys. C regulates the surface electronic properties of PdNi nanoalloys by the electron transfer between different elements and improves their activity. The PdNi@C-650 exhibits extraordinary activity and long-term stability for hydrogenation reduction of hexavalent chromium (Cr (VI)) and hydrodechlorination of chlorophenols in comparison with PdNi/CNTs (carbon nanotubes) and commercial Pd/C. Density functional theory calculations together with investigations of mechanism reveal that the high electron-deficient PdNi nanoalloys from the redistribution of electron between Ni, Pd and C of the PdNi@C-650 promote the surface adsorption of substrate molecules and H2, which accordingly enhances the hydrogenation activity. This study brings a new method for the design and preparation of high active noble metal nanoalloy.

Adsorption Mechanisms of TM3 (TM = Mo, Ru, Au)-Decorated Tin Sulfide Monolayers for the Decomposition of Gas Components under Fault Conditions in Oil-Immersed Transformers.

Oil-immersed transformers play a pivotal role owing to their environmentally friendly characteristics, compact footprint, and cost-effectiveness. Ensuring the online monitoring of oil-immersed transformers is a fundamental measure to ensure the secure and stable operation of modern power systems. In this paper, metal particle cluster-doped SnS is firstly used in the adsorption and sensing of decomposition components (CO, C2H2) under fault conditions in oil-immersed transformers. The study comprehensively analyzed band structure, differential charge density, density of states, and molecular orbital theory to unveil the adsorption and sensing mechanisms of target gases. The findings suggest that the modification of metal particle clusters can enhance the surface electronic properties of single-layer SnS. In the regions of metal particle clusters and the gas-surface reaction area, electronic activity is significantly heightened, primarily attributed to the contribution of d-orbital electrons of the metal cluster structures. The modified SnS exhibits adsorption capacity in the following order: Ru3-SnS > Mo3-SnS > Au3-SnS. Additionally, the modified material demonstrates increased competitiveness for C2H2, with adsorption types falling under physical chemistry adsorption. Different metal elements exert diverse effects on the electronic distribution of the entire system, providing a theoretical foundation for the preparation of corresponding sensors. The findings in this work offer numerical insights for the further preparation and development of SnS nanosensors, concurrently shedding light on the online monitoring of faults in oil-immersed transformers.

Impact of Synthesis Parameters upon the Electronic Structure in PVD-Deposited CdxZn1-xO Composite Thin Films: An XPS-XANES Investigation.

The impact of different synthesis parameters, such as thickness, postsynthesis annealing temperature, and oxygen gas flow rate, upon the electronic structure is discussed in detail in the present experimental investigation. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectroscopy techniques are used to evaluate the surface electronic properties along with the presence and stability of the CdO2 surface oxide in CdxZn1-xO (x = 0.4) composite thin films. The thin films were synthesized with varying thicknesses using a Cd0.4Zn0.6O (CZO) ceramic and Cd0.4Zn0.6 (CZ) metallic targets and oxygen gas flow rates during magnetron sputtering. The Zn L3,2 edge and O K edge XANES spectra are affected by the oxygen gas flow rate. For the zero rate, an increase in intensity is observed in the Zn L3,2 edge, and notable changes occur in the overall spectral features of the O K edge. In the films synthesized in the presence of oxygen, highly probable O 2p → antibonding Zn 3d electronic transitions decrease the probability of the Zn 2p1/2 → antibonding Zn 3d electronic transition by filling the vacant antibonding Zn 3d states, leading to the reduction in overall intensity in the Zn L3,2 edge. Scanning electron microscopy reveals grain growth with increasing annealing temperature. The annealing induces orbital hybridization, generating new electronic states with higher transition probabilities and intensity enhancement in both Zn L3,2 and O K edges. The presence of the CdO2 surface phase is confirmed by analyzing the Cd 3d5/2 and O 1s XPS core levels. The CdO2 surface phase is observed in the films synthesized using the CZO target for all thicknesses, while the CZ target is only observed for higher thicknesses. Further postsynthesis annealing treatment results in the disappearance of the CdO2 phase. The CdO2 surface phase can be controlled by varying the film thickness and postsynthesis annealing temperature.

Surface Electronic Properties-Driven Electrocatalytic Nitrogen Reduction on Metal-Conjugated Porphyrin 2D-MOFs.

Two-dimensional (2D) metal organic framework (MOF) or metalloporphyrin nanosheets with a stable metal-N4 complex unit present the metal as a single-atom catalyst dispersed in the 2D porphyrin framework. First-principles calculations on the 3d-transition metals in M-TCPP are investigated in this study for their surface-dependent electronic properties including work function and d-band center. Crystal orbital Hamiltonian population (-pCOHP) analysis highlights a higher contribution of the bonding state in the M-N bond and antibonding state in the N-N bond to be essential for N-N bond activation. A linear relationship between ΔGmax and surface electronic properties, N-N bond strength, and Bader charge has been found to influence the rate-determining potential for nitrogen reduction reaction (NRR) in M-TCPP MOFs. 2D Ti-TCPP MOF, with a kinetic energy barrier of 1.43 eV in the final protonation step of enzymatic NRR, shows exclusive NRR selectivity over competing hydrogen reduction (HER) and nitrogenous compounds (NO and NO2). Thus, Ti-TCPP MOF with an NRR limiting potential of -0.35 V in water solvent is proposed as an attractive candidate for electrocatalytic NRR.

Electronic Properties of F, Cl and H Atoms Adsorbed on CsPbI3(110) Surface

The electronic properties of the CsPbI3 surface are calculated by using first-principles calculations. Through calculating adsorption energy of CsPbI3 passivated by Cl, F and H atoms, it is found that adsorption energy values of CsPbI3 (110) surface passivated by H atoms fluctuate less, they are less sensitive to the adsorption position, and the adsorption is stable. Through calculating surface states of passivation system, it is found that F and H atoms have quite good passivation effect, and the Fermi level of passivation system increases and enters the forbidden band, indicating that the passivation effect is relatively ideal. Passivation effect of Cl atoms are poor, a new shallow acceptor defect states appeared at the bottom of the conduction band. This defect level could trap carriers and weaken the carrier migration ability, which is a disadvantage of Cl passivation system. Through the charge density difference and Bader charges, it is found that the F and H atoms get more electrons from the I atom, which is beneficial to the passivation of the surface states.

Single-Atom Cu-Doped TiO2 nanorods with modulated surface active sites for superior photocatalytic performance

Single-atom Cu is recently certified as an ideal metal dopant to improve the photocatalytic performance of TiO2, whereas related work is lacking to understand the correlation between the surface electronic property of the single-atom Cu-TiO2 and its photocatalytic mechanism. Herein, using the H2Ti3O7 nanowire as the precursor, the Cu-doped TiO2 nanorod (Cu1-TiO2) is prepared via a simple and in-situ strategy including the Cu+-exchange and high-temperature calcination. It is found that Cu single atoms successfully incorporate into the lattice of TiO2via occupying Ti vacancies, and the Cu1-TiO2 maintains the well-defined crystal structure of anatase. The doping Cu single atoms are theoretically simulated to induce three new states inside the bandgap of TiO2, and increase its separation efficiency of photoinduced carriers and the absorption efficiency for the visible light. Meanwhile, all O atoms around the Cu atom exhibit a weaker electron-captured ability than ones close to Ti atom, making the single-atom Cu center a strong adsorption site for the tetracycline (TC) molecule. Both the reformative band structure and the optimized adsorption behavior jointly endow the Cu1-TiO2 with a superior photocatalytic performance for the TC degradation under the irradiation of visible light. The achieved fundamental understanding of the correlation between the catalyst surface electronic property and the photocatalytic performance would provide guidelines to design more single atom photocatalysts for the possible practical applications.

Substrate Doping and Defect Influence on P-Rich InP(001):H Surface Properties

Density-functional theory calculations on P-rich InP(001):H surfaces are presented. Depending on temperature, pressure and substrate doping, hydrogen desorption or adsorption will occur and influence the surface electronic properties. For p-doped samples, the charge transition levels of the P dangling bond defects resulting from H desorption will lead to Fermi level pinning in the lower half of the band gap. This explains recent experimental data. For n-doped substrates, H-deficient surfaces are the ground-state structure. This will lead to Fermi level pinning below the bulk conduction band minimum. Surface defects resulting from the adsorption of additional hydrogen can be expected as well, but affect the surface electronic properties less than H desorption.

Insights into the Stability and Surface Termination of Topological Semimetal NbAs2

AbstractNbAs2, a topological semimetal, has stirred considerable interest for its potential usage in magnetic and fault‐tolerant quantum computation superconductor devices, owing to its superconductivity, enormous magnetoresistance, and anisotropic magneto‐transport attributes. Yet, its environmental stability, a crucial factor for practical applications, remains largely unexplored. Herein, a comprehensive examination of the stability and electronic properties of the (001) surface of NbAs2 utilizing density functional theory (DFT) and surface science experiments is conducted. The theoretical deductions reveal that As atoms, organized in a buckled honeycomb configuration, terminate the bare (001) surface, akin to the tensile blue arsenene monolayer along the armchair direction. This study further demonstrates that the oxidation barrier is particularly low (only 0.2 eV), highlighting that the (001) surface is highly prone to oxidation under standard conditions, forming a As2O5+Nb2O5/NbAs2 heterostructure. Additionally, it observes that oxidation adversely affects the electronic characteristics of the topological semimetal NbAs2. The conclusions underscore the need for NbAs2 to be managed under high vacuum conditions or to be encapsulated for any usage in the ambient atmosphere in order to retain its electronic properties for practical purposes.

Green synthesis of Fe-anchored N-doped biochar with highly active FeNx catalytic sites for electrochemical nitrate reduction

Electrocatalytic nitrate reduction reaction is regarded as the promising method to mitigate nitrate pollution and produce ammonia, but cost-effective and efficient electrocatalysts are lacking. In this study, a low-cost Fe- anchored N-doped biochar (Fe-NBC) was synthesized from the N-rich wetland plant and used for electrocatalytic nitrate reduction reaction. At optimal conditions, Fe-NBC could achieve a maximum nitrate removal capacity of 1065 mg N/g Cat, a NH3 yield rate of 78.6 umol mgcat−1 h−1, a Faradaic efficiency of 75.3 %, and an energy consumption of 0.2073 kWh/g. The kinetics results showed that the reaction rate of Fe-NBC was 1.5 times of Fe-embedded biochar, and 3.5 times of bare N-doped biochar. Experimental results and characterizations demonstrated the pyridinic-N in the form of FeNx in Fe-NBCs enhance the electrocatalytic nitrate reduction performance by modulating the electronic properties of the Fe-NBCs surface. Furthermore, the Fe-NBC cathode exhibited an excellent stability due to the coverage of Fe species by deposited carbon during the pyrolysis process. This study deepens our understanding of the role of N species on electrocatalytic nitrate reduction and provides a green strategy for fabricating efficient electrocatalyst through waste biomass.

First-principles studies on the electronic and photocatalytic water splitting properties of surface functionalized Y2C-based MXenes.

Recently, MXenes, an emerging family of two-dimensional (2D) materials, have attracted increasing interest for photocatalytic water splitting due to their various excellent physical and chemical properties, such as large specific surface area, good hydrophilicity, and remarkable light absorption ability. However, the photocatalysts of MXenes with symmetric structures are limited by rapid recombination of photo-generated carriers and the prerequisite of a large band gap no less than 1.23 eV. Differently, Janus MXenes with different surface functional groups facilitate the separation of photo-generated electrons and holes with the help of the intrinsic electric field. And, at the same time, there is no prerequisite for the band gap of Janus MXene photocatalysts as long as they possess appropriate band edge positions. Here, we explored the structural, electronic and photocatalytic water splitting properties of symmetric Y2CT2 and Janus Y2CTT' MXenes (T, T' = H, F, Cl, OH) using the density functional theory (DFT) method. Our calculations show that all the investigated Y2CT2 are not suitable photocatalysts for photocatalytic water splitting at all pH values (pH = 0, 7, and 14). In contrast, all the investigated Janus Y2CTT' MXenes are good water splitting photocatalysts with high optical absorption coefficients and remarkable solar-to-hydrogen (STH) efficiencies larger than 18% at pH = 14. Moreover, the STH efficiencies are larger than 18% even at all investigated pH values for Y2CHCl (18.5-22.6%), Y2 CFCl (∼18.7%), and Y2 C(OH)Cl (∼19.4%). Based on the first-principles calculations, we here for the first time propose an easy strategy to design Janus MXene photocatalyst candidates with possible high STH efficiency according to the electronic properties of their symmetric counterparts. Our study is helpful for the future design of Janus MXenes and more generally Janus 2D photocatalysts for water splitting with high STH efficiency.