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We have prepared a series of multiple (bi-varietal and tri-varietal) pillar-layered MOF thin films [Cu2L2dabco]n (L = bdc, bpc and tpdc) with high lattice mismatch (up to 77.8%) using a liquid-phase epitaxial layer by layer method.

PSS is a commonly used hole-transport layer (HTL) in inverted perovskite solar cells (PSCs) due to its compatibility with low-temperature solution processing. However, it possesses lower conductivity than other conductive polymers and metal oxides, along with surface defects, limiting its photovoltaic performance. In this study, we introduced two-dimensional Ti

Chiral metal-organic frameworks (chirMOFs) have been widely considered on enantioselective adsorption/separation, asymmetric catalysis, biological and nonlinear optical applications. However, chirMOFs are facing a great challenge in development of chiroptical thin films with circularly polarized luminescence (CPL) property. Here, we first report CPL thin films by encapsulating achiral lanthanide complexes Ln(acac)3 (Ln = EuaTbbGdc) into the pores of surface-coordinated chirMOF thin films (SURchirMOF) [Zn2(cam)2dabco]n with layer by layer (lbl) encapsulation strategy. Due to the unique combination of chiral porous MOF and adjustable luminescent complexes in the host-guest thin films, the obtained Ln(acac)3@SURchirMOF possess strong and tunable CPL property with high dissymmetry factors. The compared CPL and fluorescent lifetime results show that the advantage of this preparation strategy can effectively achieve energy transfer from Ln(acac)3 to SURchirMOF, resulting in an excellent CPL performance. This study not only provides a novel strategy to develop new types of chiral thin films but also offers an efficient approach for tunable chiroptical applications.

Two-dimensional (2D) metalloporphyrin-based MOF thin films possessing abundant π-π interactions are promising materials for photoelectronic devices, but no reports on fabrication of photodetectors are available so far. Herein, a series of 2D MOF Zn

The development of chiral crystalline porous materials (CPMs) containing multiple chiral building blocks plays an important role in chiral chemistry and applications but is a challenging task. Herein, we report the first example of bichiral building block based enantiopure CPM films containing metal–organic cages (MOCs) and metal complexes. The functionalized substrate was immersed subsequently into homochiral metal complex (R)- or (S)-Mn(DCH)3 (DCH = 1,2-diaminocyclohexane) and racemic Ti4L6 cage (L = embonate) solutions by a layer-by-layer growth method. During the assembly process, the substrate surface coordinated with (R)- or (S)-Mn(DCH)3 can, respectively, layer-by-layer chiroselectively connect Δ- or Λ-Ti4L6 cages to form homochiral (R, Δ)- or (S, Λ)-CPM films with a preferred [111] growth orientation, tunable thickness and homogeneous surface. The resulting enantiopure CPM films show strong chirality, photoluminescence, and circularly polarized luminescence (CPL) properties as well as good enantioselective adsorption toward enantiomers of 2-butanol and methyl-lactate. The present in situ surface chiroselective strategy opens a new route to assemble homochiral CPM films containing multiple chiral building blocks for chiral applications., Bichiral building block based enantiopure CPM films containing metal–organic cages (MOCs) and metal complexes are chiroselectively assembled on the substrate surface by a layer-by-layer method.

Herein we report a 2D surface-coordinated porphyrinic metal-organic framework film (SURMOF) CuTCPP prepared by a layer by layer method as an optical limiting layer in a polymer-dispersed liquid crystal (PDLC) device. The results show that the CuTCPP SURMOF/PDLC device has excellent switchable transparency and optical limiting performance, providing a new route to achieve mutilfunctional electro-optical applications.

Fabrication of metal-organic frameworks (MOFs) thin films has been an efficient way to expand their functionalities and applications. Here, we use the vapor-assisted deposition (VAD) method to epitaxially grow a porphyrin-based MOF PCN-222 film. That is, vapor source assists to deposit pre-treated precursor solution on quartz substrate to form a continuous PCN-222 film. Furthermore, utilizing the post-treated encapsulation of functional carbon-based nanoparticles, the carbon nanodots (CND) and Pt doped CND (Pt/CND) are well loaded into the pores of PCN-222 film, the size (~3.1 nm) of which is highly close to the pore size of the corresponding MOF (~3.7 nm). The Z-scan results reveal that PCN-222 film exhibits high reverse saturable absorption. In addition, encapsulation of carbon based nanodots into PCN-222 film could enhance the nonlinear optical limiting effect benefiting from the host-guest combination. This study serves to present both the available toolbox of thin film preparation and high potential for precise synthetic nanocomposite films in optical limiting devices.

Development of covalent organic frameworks (COFs) with circularly polarized luminescence (CPL) is still challenging. Here we first reported ultrathin COFs nanosheets (NS) based CPL materials using a chiral induced-synthesis strategy. Chiral amines served as chiral inducers to give COF TpBpy with chirality and participated in the modification of TpBpy, inhibiting the fluorescence quenching caused by π-π stacking to form ultrathin luminescent chiral COFs (chirCOFs) NS. The obtained chirCOFs

Cerium (IV)-based metal-organic frameworks (MOFs) are highly desirable due to their unique potential in fields such as redox catalysis and photocatalysis. However, due to the high reduction potential of Ce(IV) species in solution, it is still a great challenge to synthesize Ce(IV)-MOFs with novel structures, which are extremely dominated by the hexanuclear Ce-O cluster inorganic building units (IBUs). Herein, a Ce-O chain IBU containing Ce(IV)-MOF CSUST-3 (CSUST: Changsha University of Science and Technology) was successfully prepared guided by the kinetic stabilization study of UiO-66(Ce)-NDC (H 2 NDC = 2,6-naphthalenedicarboxylic acid). Furthermore, owing to the superior redox activity, Lewis acidity and semiconductor-like behavior incurred by Ce 4+ , activated CSUST-3 was demonstrated to be an excellent catalyst for CO 2 chemical fixation by virtue of one-pot synthesis of styrene carbonate from styrene and CO 2 under mild conditions (1 atm CO 2 , 80 °C, and solvent-free), as well as to be a remarkable co-catalyst-free photocatalyst for overall water splitting (OWS), which exhibits 59 μmol∙g -1 ∙h -1 of H 2 and 22 μmol∙g -1 ∙h -1 of O 2 under simulated sunlight irradiation (Na 2 S-Na 2 SO 3 as sacrificial agent).

Electron delocalization in aromatic materials significantly impacts their third-order nonlinear optics (NLO). Despite organometallic complexes with Craig-Mobius aromaticity attracting great attention for their unusual physicochemical properties, their third-order NLO have been little studied to date. Herein, 12 Craig-Mobius aromatic organometallics with a stable structure similar to osmapentalyne, namely, carbolong complexes, are screened by DFT. They exhibit high third-order NLO responses because of the d and p electron delocalization in the organometallic ring. Furthermore, electron-hole distribution analyses draw a conclusion that extending the conjugated plane will increase the π-conjugation system to enhance the local excitation in the plane, and the introduction of typical aromatic ligands can result in the organometallic ring-to-ligand charge transfer (RLCT), which are effective methods to improve the third-order NLO response. This study opens a new window in the application of Craig-Mobius aromatic complexes and provides a new approach for third-order NLO materials design.

The development of metal-organic frameworks (MOFs) with nonlinear optical (NLO) properties is of pronounced significance for optical devices. Herein, a series of 2D MOFs ZnTPyP(M) (TPyP = 5,10,15,20-tetrakis(4-pyridyl)porphyrin, M = Cu, Ni, Mn, H2) films with [010]-orientation growth composed of ultrathin nanosheets from a pyridylporphyrinic ligand are first obtained by using a liquid-phase epitaxial (LPE) layer-by-layer (lbl) growth approach. ZnTPyP(M) films show a giant nonlinear optical limiting (OL) response and can be modulated by tuning the type of metalloporphyrinic ligands. As a result, ZnTPyP(Cu) film exhibits the highest nonlinear absorption coefficient of 5.7 × 10-6 m/W compared to other reported NLO materials. Density functional theory calculations were consistent with the experimental results, revealing that the tunable π-π* local excitation and the increased delocalization of the metalloporphyrinic group regulate the NLO performance of ZnTPyP(M) films. These findings provide new insight into the effect of 2D porphyrinic MOFs toward the NLO response and offer new film candidates for nonlinear OL application.

Cerium (IV)-based metal-organic frameworks (MOFs) are highly desirable due to their unique potential in fields such as redox catalysis and photocatalysis. However, due to the high reduction potential of Ce

Metal–organic frameworks (MOFs) with third-order nonlinear optical (NLO) properties are still in their infancy but are very important. In this work, we first develop a layer by layer autoarm immersion method for preparing porphyrin-based MOF (PIZA-1) thin films with third-order NLO properties. By precisely controlling the thickness, the nonlinear absorption of PIZA-1 thin films can be switched continuously between reverse saturable absorption (RSA) and saturable absorption (SA) by using the Z-scan technique. In addition, the optical limiting effect could be further optimized by loading C60 in the pores of the PIZA-1 thin film. These findings not only open a new route for the exploitation of third-order NLO thin film materials, but also offer an insightful understanding of porphyrin-based MOF thin films for future broad practical applications., A layer by layer autoarm immersion method is developed to prepare metal-porphyrin thin films with third-order NLO properties.

Bifacial dye-sensitized solar cells (DSSCs) are regarded as promising solar energy conversion devices with high efficiency and less resource consumption. In this work, a highly transparent and efficient counter electrode (CE) is fabricated by introducing highly dispersed single Pt atoms doped into the van der Waals layer-by-layer epitaxially grown Zn-TCPP thin film (Zn-TCPP-Pt). The resulting Zn-TCPP-Pt CE has similar catalytic activity to commercial Pt CE but shows a better light transmission capacity in the range of visible light. The bifacial DSSC with Zn-TCPP-Pt thin film CE achieves high power conversion efficiencies of 5.48 and 4.88% under front-side and rear-side irradiation, respectively. With maximized atomic efficiency, excellent performance was obtained with about 1% Pt content and highly transparent CEs. Therefore, the light energy resource utilization rate of such less Pt and transparence CE is greatly improved in bifacial dye-sensitized solar cells, making it a promising candidate to replace Pt CE.

The development of cost-effective, high-efficiency, and non-noble metal based electrocatalysts for oxygen evolution reaction (OER) is considered to be the most pivotal portion for electrochemical water splitting to generate renewable energy. Herein, well-aligned mesoporous CoFe2O4 thin film is first developed from surface epitaxial growth of oriented CoFe-based prussian blue analogue thin film (CoFe-PBA thin film) for efficient electrocatalytic OER. CoFe-PBA thin film with preferred [100] orientation is first prepared on the substrate surface by employing liquid phase epitaxial method without any structure-directing surfactants. After thermal pyrolysis, such CoFe-PBA thin film was transformed into well-aligned mesoporous CoFe2O4 thin film. Interestingly, the self-support CoFe2O4 thin film electrode with the mass loading of 1.6 mg cm−2 delivers an oxygen evolution current density of 10 mA cm−2 at an overpotential of 266 mV and exhibits durable stability in 1 M KOH aqueous solution. The remarkable and stable catalytic performance of the CoFe2O4 thin film can be mainly owing to the mesoporous structure of CoFe2O4, efficient charge/electron transfer, the numerous exposed active sites, and the well-structured configuration of the electrode. Hence, this work provides an effective paradigm for preparing binder-free, self-support, and low-cost spinel oxide electrocatalyst for efficient OER derived from surface epitaxial growth of oriented PBA thin film.

The potential of metal–organic frameworks (MOFs) for applications in optoelectronics results from a unique combination of interesting photophysical properties and straightforward tunability of organic and inorganic units. Here, it is demonstrated that using MOF approach chromophores can be assembled into well‐ordered 1D arrays using metal‐oxo strands as lead structure, and the resulting porphyrinic rows exhibit unique photophysical properties and allow the realization of highly sensitive photodetectors. A porphyrinic MOF thin film, In‐TCPP surface‐coordinated MOF thin films with [021] orientation is fabricated using a layer‐by‐layer method, from In(NO3)3 and TCPP (5,10,15,20‐(4‐carboxyphenyl)porphyrin). Detailed experimental and theoretical analysis reveals that the assembly yields a structure where In‐oxo strands running parallel to the substrate fix the chromophoric linkers to yield 1D arrays of porphyrins. The frontier orbitals of this highly anisotropic arrangement are localized in these columnar arrangements of porphyrins and result in high photoactivity, which is exploited to fabricate a photodetector with record (as compared to other organic materials) responsivity in visible regime of 7.28 × 1014 Jones and short rise/fall times (0.07/0.04 s). This oriented MOF thin film‐based high‐sensitive photodetector provides a new avenue to use inorganic, stable lead structures to assemble organic semiconductors into regular arrays, thus creating a huge potential for the fabrication of optoelectronic devices., Highly photoactive, porphyrinic metal–organic framework (MOF) thin films are grown on substrates using layer‐by‐layer process. The unusual architecture of this particular MOF consists of In‐oxo chains acting as lead structure to obtain highly ordered 1D arrays of porphyrins. The MOF thin film is successfully integrated in a visible light photodetector with record sensitivity, 7.28 × 1014 Jones.

N-heterocyclic carbenes (NHCs) have attracted increasing attention on surface assembly due to their strong metal binding property, but an NHC-modified metal surface as a new growth platform to assemble other functional materials is still a challenge. Here, we report the preparation and chiral sensing properties of homochiral metal-organic framework thin films on carboxyl-containing NHC self-assembled monolayer-modified gold (Au(NHC)) substrates. By using a liquid-phase epitaxial layer-by-layer method, enantiopure [Cu2(cam)2dabco]n thin films with preferred [110] crystal orientation have been successfully grown on Au(NHC) surfaces. The results of electrochemical cyclic voltammetry and quartz crystal microbalance uptakes of (R)- and (S)-1-phenylethanol show that the chiral porous thin film on the robust Au(NHC) surface has good enantiomeric electrochemical recognition and enantioselective adsorption. The present work is a new step to develop metal-NHCs as surface platforms for the preparation of multifunctional thin films for sensing applications.

Thin film materials have been used widely in semiconductor devices, including solar cells, transistors, light emitting diodes, light crystal displays, smart windows, chips as well as temperature and gas sensors. As multilayer materials with nanometers in thickness, metal–organic framework (MOF) thin films have been increasingly investigated due to their potential applications in molecular recognition/separation, catalysis, sensors and devices. In this review, we will summarize recent works focusing on epitaxial growth and applications of surface-mounted MOF thin films (SURMOFs) and encapsulated SURMOFs on substrate surfaces. Such oriented, compact and homogenous thin films provide a promising model for studying the crucial intrinsic properties in coordination chemistry, growth mechanism, chiral chemistry and the guest diffusion behavior in MOFs system. Their related applications on molecular adsorption and separation, optical applications, organic field effect transistors and catalysis are also descripted in this review. This review will be of interest to researchers on attempting to design other multifunctional MOF thin films and those engage in the extension of thin films to particle applications of sensors and devices.

Developing efficient and inexpensive oxygen evolution reaction (OER) catalysts is one of the critical issues in energy storage and conversion technology. Herein, an oriented thin film of 3-D MOF Co/Ni(BDC)2TED (BDC = 1,4-benzenedicarboxylate; TED = triethylenediamine) nanosheet arrays is first obtained on Cu foam by a liquid-phase epitaxial layer-by-layer growth approach. The obtained thin film of bimetallic MOF nanosheet arrays has preferred growth with [001]-orientation and strong adhesion on the substrates without the use of binder materials, which provides more accessible active sites for electrocatalytic performance. The OER activity of such surface-mounted MOF nanosheet arrays can be optimized effectively via tuning the thicknesses and Co/Ni ratios. The Co/Ni(BDC)2TED grown on Cu foam with 40 cycles at a Co/Ni ratio of 1/1 shows superior OER activity with required overpotentials of 260 and 287 mV to achieve current densities of 10 and 50 mA cm−2 and excellent stability. The experiments and theoretical calculations reveal that the synergistic effect of Co/Ni and rich metal sites dominated by nanosheet interfaces improve the electrocatalytic activity. This work provides more insight into the OER activity of the MOF thin film as an electrode material and presents a new strategy for developing promising highly efficient electrocatalysts in practical applications.

The realization of encapsulating a functional guest into porous metal–organic frameworks-based thin films for optimizing and improving electrocatalysis remains a significant challenge. In this work, an Fe bis(salicylaldehyde)ethylenediimine (Salen) compound Fe(Salen) encapsulated cobalt-porphyrin framework PIZA-1 (Fe(Salen)@PIZA-1) thin film with different surface compositions was successfully developed by using a modified epitaxial layer-by-layer approach. After calcination, this composite Fe(Salen)@PIZA-1 derived thin film is first developed as oxygen evolution catalyst which attained precise control on the surface composition. The electrochemical results showed that this unique surface modified material has a good catalytic activity for OER (η = 340 mV at 10 mA cm–2) and long-term stability. This strategy gives an insight into developing a highly active, nonprecious encapsulated thin film in electrochemical energy devices.

The development of clean and sustainable energy is crucial to solve the increasingly serious energy crisis. Metal-organic frameworks (MOFs) containing both inorganic and organic components have attracted extensive attention on energy applications because of their tunable structures and fascinating properties. Particularly, liquid-phase epitaxial (LPE) layer by layer (LBL) growth of MOFs thin films on various substrates surfaces (called SURMOFs, surface-coordinated MOF thin films) possess the advantages of controlled thickness, preferred growth orientation and homogeneous film, which provide ideal candidates for energy storage and conversion. In this review, we summarize the fabrication strategies of SURMOFs including the layer by layer dipping, pump, spray, spin-coating and flowing methods, the classification and advantages of SURMOFs, and then discuss the related energy applications of SURMOFs, encapsulated SURMOFs, and SURMOF-derivative on electrocatalysis, photocatalysis, and solar cells etc.

The development of new non-platinum catalysts for alcohol electrooxidation is of utmost importance. In this work, a bimetallic Pd–Cu loaded porous carbon material was first synthesized from a Cu-based metal–organic framework (MOF). The Cu loaded porous carbon was pre-synthesized through calcinating the Cu-based MOF under a N2 atmosphere. After loading Pd onto the precursor and heating, Pd–Cu loaded porous carbon (Pd–Cu/C) was obtained for alcohol electrooxidation. Electrooxidation experiments revealed that this Pd–Cu bimetal loaded porous carbon assisted steady state electrolysis for alcohol oxidation in alkaline media. Moreover, different alcohols were electrooxidated using the present electrocatalyst for the purposes of discussing the oxidation mechanism. This electrooxidation study of Pd–Cu/C derived from a MOF demonstrates a good understanding of the electrooxidation of different alcohols, and provides useful guidance for developing new electrocatalyst materials for energy conversion and electronic devices.

Here we report an effective approach for preparing hollow carbon nanospheres with Cu–TiO2 from a Ti precursor encapsulated surface mounted MOF (SURMOF) coating. Firstly a core–shell structured Cu-based SURMOF HKUST-1 on SiO2 nanospheres (SiO2@HKUST-1) with a thin and homogeneous shell coating has been prepared by a liquid-phase epitaxial layer by layer immersion method. Then the uniform SiO2@HKUST-1 nanospheres were loaded with a Ti precursor Ti(O-ipr)4, followed by calcination at 800 °C; hollow carbon nanospheres with Cu–TiO2 (Cu–TiO2/C) could be obtained after etching SiO2 nanosphere templates. As a result of their unique structure, such hollow, thin, uniform and homogeneous Cu–TiO2/C nanospheres had efficient photocatalytic H2 production and excellent recyclability under simulated sunlight irradiation. The method developed here provides a new approach for the preparation of hollow hybrid carbon nanospheres with various applications.

The use of 2-naphthalenesulfonate (NAS) ligand in lanthanide chemistry afforded a family of isostructural mononuclear lanthanide complexes with the formula [Ln(NAS)2(H2O)6](NAS)·3H2O [Ln = Tb (1), Dy (2), Er (3), Yb (4)]. Crystallographic studies determined a square antiprismatic geometry (D4d) for the Ln centre and crystallization in an unprecedented chiral space group. The latter was further confirmed by the observation of Cotton effects in single crystal circular dichroism (CD) spectra. Static and dynamic magnetic measurements identified weak intermolecular dipolar interactions in 2, and such effects can be waived by dilution, which was noted by the detection of zero-field single molecule magnet (SMM) behaviour and hysteresis loop in a magnetically diluted sample (5). Compounds 2-4 exhibit SMM behaviours with energy barriers of 53, 32, and 45 K, respectively. To the best of our knowledge, these complexes are the first examples of pure 4f sulfonate-based SMMs.

Arrays of ultrasmall and uniform carbon nanodots (CDs) are of pronounced interest for applications in optical devices. Herein, we describe a low-temperature calcination approach with rather inexpensive reactants. After glucose molecules had been loaded into the pores of metal-organic frameworks (MOFs), well-defined CD arrays were produced by heating to 200 °C. The size and spacing of the CDs could be controlled by the choice of templating MOF: HKUST-1, ZIF-8, or MIL-101. The sizes of the obtained CDs were approximately 1.5, 2.0, and 3.2 nm, which are close to the corresponding MOF pores sizes. The CD arrays exhibited interesting photophysical properties, including photoluminescence with tunable emission and pronounced nonlinear optical (NLO) effects. The NLO properties of the obtained CD arrays were significantly different from those of a CD suspension, thus indicating the existence of collective phenomena.

We report a facile approach to prepare metal-nanocatalyst-incorporated carbon thin films with uniform size distribution via carbonization of surface-mounted metal-organic frameworks (SURMOFs) and metal oxo-clusters loaded SURMOF. The calcinated thin films have high performance of methylene blue degradation and the reduction of nitrobenzene. This study describes a general strategy for preparing various nanoparticle-impregnated porous carbon thin films for applications in catalysis.

Metal–organic framework (MOF) thin films are important in the application of sensors and devices. However, the application of MOF thin films in organic field effect transistors (OFETs) is still a challenge to date. Here, we first use the MOF thin film prepared by a liquid-phase epitaxial (LPE) approach (also called SURMOFs) to modify the SiO2 dielectric layer in the OFETs. After the semiconductive polymer of PTB7-Th (poly[4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]) was coated on MOF/SiO2 and two electrodes on the semiconducting film were deposited sequentially, MOF-based OFETs were fabricated successfully. By controlling the LPE cycles of SURMOF HKUST-1 (also named Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylate), the performance of the HKUST-1/SiO2-based OFETs showed high charge mobility and low threshold voltage. This first report on the application of MOF thin film in OFETs will offer an effective approach for designing a new kind...

Development of chiral metal-organic frameworks (MOFs) for circularly polarized luminescence (CPL) is a challenging but important task. In this work, we report a first example of azapyrene-based chiral MOF thin films [Zn2Cam2DAP]n grown on functionalized substrates (named SURchirMOF-4) for CPL property. By using a liquid-phase epitaxial layer-by-layer method, the resulted SURchirMOF-4 was constructed from chiral camphoric acid and 2,7-diazapyrene ligand, which has high orientation and homogeneity. The circular dichroism, CPL, and enantioselective adsorption results show that SURchirMOF-4 has strong chirality and CPL property as well as good enantioselective adsorption toward enantiomers of methyl-lactate. The synthesis of azapyrene-based chiral MOF thin films not only represents an ideal model for studying the enantioselective adsorption, but also will be a valuable approach for development of the chiral thin film exhibiting CPL property.

A self-polymerized chiral monomer 3,4-dihydroxy-l-phenylalanine (l-DOPA) has been introduced into the pores of an achiral surface-mounted metal organic framework (SURMOF), and then the homochiral poly(l-DOPA) thin film has been successfully formed after UV light irradiation and etching of the SURMOF. Remarkably, such a poly(l-DOPA) thin film exhibited enantioselective adsorption of naproxen. This study opened a SURMOF-templated approach for preparing porous polymer thin films.

A palladium catalyst (Pd-Cs) encapsulated metalloporphyrin network PIZA-1 thin film with bifunctional properties has been developed through a modified epitaxial layer-by-layer encapsulation approach. Combining the oxidation activity of Pd-Cs and the acetalization activity of the Lewis acidic sites in the PIZA-1 thin film, this bifunctional catalyst of the Pd-Cs@PIZA-1 thin film exhibits a good catalytic activity in a one-pot tandem oxidation-acetalization reaction. Furthermore, the surface components can be controlled by ending the top layer with different precursors in the thin film preparation procedures. The catalytic performances of these thin films with different surface composites were studied under the same conditions, which showed different reaction conversions. The result revealed that the surface component can influence the catalytic performance of the thin films. This epitaxial encapsulation offers a good understanding of the tandem catalysis for thin film materials and provides useful guidance to develop new thin film materials with catalytic properties.