Insight into Fe(Salen) Encapsulated Co-Porphyrin Framework Derived

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Insight into Fe(Salen) Encapsulated Co-Porphyrin Framework Derived Thin Film for Efficient Oxygen Evolution Reaction Salma Mirza, Hao Chen, Shu-Mei Chen, Zhi-Gang Gu, and Jian Zhang Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b01300 • Publication Date (Web): 02 Oct 2018 Downloaded from http://pubs.acs.org on October 3, 2018

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Crystal Growth & Design

Insight into Fe(Salen) Encapsulated Co-Porphyrin Framework Derived Thin Film for Efficient Oxygen Evolution Reaction Salma Mirza,†‡ Hao Chen,† Shu-Mei Chen,§ Zhi-Gang Gu†* and Jian Zhang† †

State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure

of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China. ‡

University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.

§

College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, P. R. China

ABSTRACT: The realization of encapsulating functional guest into porous metal-organic

frameworks-based thin films for optimizing and improving electrocatalysis remains a significant challenge. In this work, a 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 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 highly active, nonprecious encapsulated thin film in electrochemical energy devices.

KEYWORDS: epitaxial encapsulation; Co-porphyrin framework thin film; oxygen evolution reaction; Fe(Salen) compound

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Introduction High energy demand is one of the serious concerns for modern society because of the low availability and severe environmental damage concerns. Nowadays, production of energy from conversion resources has been still a significant challenge. Water splitting is considered as a key reaction to enable the energies storage and conversion, providing a source with clean and renewable energy.1, 2 As one of the most significant processes, the oxygen evolution reaction (OER) has attracted academic and technological interests in the electrocatalytic synthesis in recent years.3-7 The development of the active, stable and cost-effective oxygen evolution catalysts (OECs) is important half-reaction in water splitting.8-11 An extensive study has been carried out on economical transition metal oxides (or oxy/hydroxides) for the forefront of the OECs with low overpotential and highly catalytic activity. Pt, Ru, and Ir transition metals renowned for OER electrocatalysts but exhibited moderate overpotential.12 Generally, these transition metal based electrocatalysts are decorated on conductive supports which have high surface area to ease the diffusion of electrons and increases active catalytic sites. However, complications in electronic conductivity, active sites and compositional relationships and structure remain unclear which makes it a hot topic of research interest. One of the major benefits of nanoscale catalysis is to reduce the use of noble metal and providing a large catalytic active surface area with respect to volume. Recently, metal–organic frameworks (MOFs) contain hetero-transition metal ions or hetero-functional ligands provide a metal-rich platform for the oxygen evolution catalysts (OECs).13-16 Even though, electrocatalyst from powder MOF


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with mixed orientations is usually needed to deposit it on glassy carbon electrode in which provide small surface area as well as affect mass activity.17 Probably this challenging situation with great limitation in producing a homogenous distribution of different metal ions is concerned. So, highly oriented MOF thin films with a homogenous surface will overcome these limitations specifically electrochemically accessible surface area, low porosity and slow diffusion of electrons.18 Particularly MOF thin films prepared by liquid phase epitaxial (LPE) method on a variety of substrates are known as surface-mounted metal-organic frameworks (SURMOFs). As a kind of special MOF thin films, SURMOFs have been widely used for various applications.18-20 Additionally, introduction of a guest catalyst in the pores of the MOFs thin film by means of epitaxial encapsulation method21, 22 will offer an opportunity for increasing the efficiency of OECs. In the present work, we report the synthesis (Scheme 1) of non-precious metal-based electrocatalyst and insights to the intrinsic activity for the OER on [110]-orientation of guest encapsulated MOF derived thin film in alkaline solution. Apart from other reported synthesis protocols, such as random mixing of hetero-metal Fe and Co centers on support materials which makes it difficult to achieve precise ordered active electrocatalytic species.23,24 It can be achieved by controlling the Fe and Co metal composition along with rigid frameworks in a MOF derived thin film, which also help to retain porosity and the heteroatom position in carbonized materials which could be a unique strategy to develop highly performance OECs. Firstly, we selected PIZA-1 MOF comprises of cobalt tetra-p-carboxyphenylporphyrin complexes which linked via carboxylate coordination to trinuclear cobalt (Co2+, Co3+)



oxo-clusters. As extensive literature survey showed that cobalt based materials are one of the known non-noble catalyst with high OER potential14 and porphyrin with interesting properties in improving the catalysis and conductivity.25-27 Secondly, we choose Fe(Salen) guest catalyst to introduce into the pores of the MOF thin film. Furthermore, Fe(Salen) is isolated compound and can be easily incorporated into the MOF pores homogenously which serves as co-catalyst. The high abundance, low cost, and nontoxicity, Fe-based OECs reflects good OER activity by serving as co-catalyst such as, in combination with metal oxides and hydroxide improve OER by lowering overpotential than without Fe catalyst.28-29 For the above mentioned reasons Fe(Salen) with a nitrogenous tetradentate ligand was selected as a guest for encapsulating into the 3D PIZA-1 MOF. This work establishes an effective technique to improve heterometallic and oriented MOFs-based catalytic agent by integrating MOFs with isolated guest molecule through an epitaxial process which provides an opportunity to tune and balance the activity of electrocatalyst.


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Scheme 1. Schematic representation of encapsulating guest into MOF PIZA-1 thin film on solid substrate by using epitaxial encapsulation method. Experimental section Materials and Instruments All reagents were commercially available and used without any purification. The samples grown on functionalized substrate (FTO and Si wafer) were characterized with Powder X-ray diffractometer (PXRD, MiniFlex2 X-ray diffractometer) using Cu-Kα radiation (λ = 0.1542 nm) with a scanning rate of 0.5° min−1. Scanning electron microscope (SEM) images for the morphology of thin films were measured by JSM6700. The samples were characterized by ATR-FTIR, Fourier Transform Infrared reflection absorption spectroscopy (Bruker Vertex 70), 1

H-NMR (AVANCE III, Nuclear Magnetic Resonance Spectrometer) and HR-MS (High

Resolution Mass Spectrometer). Electrochemical measurement was carried out by CHI-760E



(Shanghai

Chenhua

Instrument China) electrochemical

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work

station and

X-Ray

Photoemission Spectroscopy (XPS) analysis (ESCALAB 250Xi) has been carried out to examine, elemental composition and their micro level structural morphology studied. Synthesis of Salen (Shiff Base) A mixture of 2-hydroxybenzaldehyde and ethane-1,2-diamine (2:1) mole ratio were placed in round bottom flask with reflux in ethanol to 80 oC for 2h. The resulted product bis(salicylaldehyde)ethylenediimine (Salen, yellow crystals) was filtered and washing with ethanol, dried and confirmed by MS and 1H-NMR spectroscopy (Figure S1, S3 Supporting Information).

Synthesis of Fe(Salen) A mixture of FeCl2•2H2O (0.25mmol) and bis(salicylaldehyde)ethylenediimine (Salen) (0.75 mmol) were placed in a 20 mL of sealed glass bottle with 5 mL pure ethanol. The mixture was ultrasonicated for 30 min and then was heated at 80 ºC for 2 days, resulting in the formation of a brown solution. After evaporation of this solution and washing, the brown powder of compound Fe(Salen) (bis(salicylaldehyde)ethylenediimine(Fe)) was obtained and characterized by MS and 1H-NMR spectroscopy (Figure S2, S4 Supporting Information).


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Functionalization of FTO substrate The functionalized FTO substrates were treated with a mixture of concentrated KOH (2mmol) aqueous solution and hydrogen peroxide (30 %) with a volume ratio 3:1 at 80 °C for 30 minutes and then washing with deionized water and EtOH followed by drying under nitrogen flux for the next preparation. Fabrication of Fe(Salen)@PIZA-1 thin films The thin film was fabricated using the following diluted ethanolic solutions: cobalt (II) acetate (1 mM) and TCPP (0.1 mM) and Fe(Salen). The spray times were 15s, 25s and 10s for Co(OAc)2 and TCPP Solution and Fe(Salen) (0.1 mM) ethanolic solutions sequentially. The interval time for each step was 30s followed by a 3s spray with pure ethanol to remove residual reactants. In this work a fabrication of thin film with repeated growth cycles were used for LPE layer-by-layer Fe(Salen) encapsulation in PIZA-1 (Fe(Salen)@PIZA-1) thin film. Fabrication of Fe(Salen)@PIZA-1-400 thin film on FTO The sample of Fe(Salen)@PIZA-1 thin films were placed in a tubular furnace and calcinated at 400 oC with flowing N2 for 4 h. The sample was cooled at room temperature to obtained the desired Fe(Salen)@PIZA-1-400 thin film on FTO. Further tuning of surface composition of SURMOF by engineering the top layer morphology in the final spray cycle of LPE with Co(OAc)2, TCPP and guest Fe(Salen) which remained as a top layer thin film. Their



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electro-catalytic performances and influence of top layer morphology was further studied.

Results and Discussion The

organometallic

precursor

Fe(Salen)

was

synthesized

by

first

prepare

bis(salicylaldehyde)ethylenediimine (Salen) via mixing of 2-hydroxybenzaldehyde with ethane-1,2-diamine in (2:1) ratio reflux in ethanol to obtain yellow crystals of Salen and next [bis(salicylaldehyde)ethylenediimine(Fe)] prepared by adding Fe (II) salt to afford Fe(Salen) by the solvothermal method and confirmed by MS and 1H-NMR spectroscopy (Figure S2, S4 Supporting Information). To access the electrochemical performance of Fe(Salen) encapsulated PIZA-1 MOF we choose a substrate which is conductive and transparent FTO (Fluorine-doped Tin Oxide) glass. The fabrication of thin film is schematically shown in Scheme 1. Besides, iron (III) oxide (Fe2O3) has been used as anode material because of the abundance, stability, corundum structure and appropriate band gap and suitable positive valence band which could serve as a cocatalyst to improve electrocatalytic performance.30-32 Fe(Salen) could be converted to Fe2O3 after calcination. Moreover, we prepared three samples to study the effect of surface layer on Fe(Salen)@PIZA-1 derived thin film for OER, i.e., top layer stopped at Co(OAc)2, TCPP and Fe(Salen) termed as Fe(Salen)@PIZA-1[Co], Fe(Salen)@PIZA-1[TCPP] and Fe(Salen)@PIZA-1[Fe]. Figure 1a shows Powder X-ray diffraction (PXRD) spectrum of the as-synthesized encapsulated PIZA-1 thin film diffraction data as a function of the out-of-plane peak at 6.1o and 12.2o recognized as the [110] orientation compared to simulated PIZA-1 thin film. In our previous work, we studied that PIZA-1 thin films with different controllable groups that remained stable and gave a good electrochemical performance at 400 oC calcination


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temperature, above this temperature it affects the stability as well as the electrochemical property of the thin film.20 In addition, it is difficult to observe the changes in guest molecule after calcination of Fe(Salen)@PIZA-1 encapsulated SURMOF. Because it has different kinds of species collectively PIZA-1 and Fe(Salen), it can be transformed into porous carbon and nitrogen-rich material when brought to calcination. So, we first calcinated Fe(Salen) separately to 400 oC (Fe(Salen)-400) and its characterization has been carried out to present here insights of guest molecule loaded in PIZA-1 SURMOF and their effect on OER performance. The PXRD patterns (Figure 2a) of Fe(Salen)-400 displayed various oxides diffraction peaks and can be indexed to those in the JCPDS data (JCPDS No. 40-1139) and (JCPDS No. 54-0489) for Fe2O3. A Raman characterization (Figure S5) demonstrated the intense absorbance at 300 to 700 cm-1 in the active modes of Fe2O3 for Fe(Salen)33,34 and the absorbance from 1200~1600 cm-1 from metalloporphyrin group. However, the loss of -OH absorbance peak at 3000 cm-1 in the IR (Figure S6) from the calcined Fe(Salen)@PIZA-1-400 suggests that metalloporphyrin lost -OH feature after calcination.35



Fe(Salen)@PIZA-1

900 PIZA-1 [110]

Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Simulated powder PIZA-1

600 Fe(Salen)-400

Fe2O3 (JCPDS No: 40-1139)

300

Fe2O3 (JCPDS No: 54-0489)

0 5

10

15

20

25

30

35

40

45

2 Theta Figure 1. XRD of Fe(Salen)@PIZA-1, simulated PIZA-1, Fe(Salen)-400 and Fe2O3. The result demonstrated that some of the material converted to graphitic carbon after calcination of Fe(Salen). Figure S5 confirm that two characteristic bands at 1345 and 1590 cm−1 which are the D (disorder-induced phonon mode) and G bands (graphitic lattice mode E2g)36 bands respectively for graphitic carbon are present after calcination to 400 oC temperature. The calculated ID/IG ratios of Fe(Salen) and Fe(Salen)@PIZA-1-400 are 0.85 and 0.88 respectively clearly indicated the defective nature of Fe(Salen)@PIZA-1-400 because of its porous nature. This deduced that the source of graphitic carbon should be as a result of Fe(Salen) calcination. This indicated that the resultant composite contained certain amount of graphitic carbon after calcination. SEM images (Figures 2a and b) displayed the homogenous sheet-like surface morphology before and after calcination of PIZA-1 MOF thin film.


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Elemental mapping of SEM (Figure 2c) confirmed that Fe, Co, C, N, and O were evenly distributed on their expected sites homogeneously.

(b)

(a)

2 µm

2 µm (c)

6 µm

6 µm

O

6 µm

C

6 µm

N

6 µm

Fe

6 µm

Co

Figure 2. (a) SEM image before and (b) after calcination to 400 oC, its corresponding EDS mappings for (c) carbon, nitrogen, oxygen, cobalt and iron for the corresponding Fe(Salen)@PIZA-1[Fe]. Since the Co/Fe based materials are good candidates for electrocatalysis, the chemical composition and nitrogen bonding configuration in the Fe(Salen)@PIZA-1 were studied through X-ray photoelectron spectroscopy (XPS) measurements. Table S1 displayed the surface atomic percentage of all the elements of the three encapsulated SURMOF samples (named

Fe(Salen)@PIZA-1-400[Fe],

Fe(Salen)@PIZA-1-400[TCPP]).

The

high-resolution

Fe(Salen)@PIZA-1-400[Co], XPS

spectrum

of

C1s

for

Fe(Salen)@PIZA-1-400[Fe] in which top layer stopped at Fe(Salen) deduced into four



deconvoluted peaks: C-C (284.8 eV), C=C (284.4 eV), C=N (285.4 eV), C-O (286.2 eV), (Figure S8).37-39 The high-resolution nitrogen fitting N1s of XPS spectrum deconvoluted into various nitrogen peaks at pyrrolic N (399.8 eV), Co-N (399.6 eV), quaternary amine N (401 eV), graphitic N (401.8 eV) and pi-pi satellite at 407 eV (Figure 3b).40 Comparatively the Co-N content is very less in without calcined Fe(Salen)@PIZA-1 MOF thin film and also no graphitic N content, this suggesting that high content of Co-N and graphitic N should be beneficial for OER activity.

Figure 3. XPS data of Nitrogen in the sample of (a) Fe(Salen)@PIZA-1[Fe], and (b) Fe(Salen)@PIZA-1-400[Fe] (c) Co and (d) Fe of Fe(Salen)@PIZA-1-400[Fe] In addition, metal oxides were also detected in high resolution XPS spectrum (Figure 3d)


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showed the existence of Fe2+ (711 and 724 eV) and Fe3+ (714 and 726 eV) along with a satellite peak at 719.4 eV, which confirmed that most of the Fe is in Fe3+ oxidation state in the thin film composite.41-43 The presence of Fe3+ after the calcination can be clearly demonstrated by the XPS data. The peak in Fe 2P3/2 XPS spectrum at 714 eV evidences for the presence of Fe3+species an important factor for such OER activity, as Fe3+ sites offer ideal binding energy for the −OH and −OOH to stabilize -OOH intermediate species which eventually result in the evolution of oxygen.40, 44, 45 And Co 2p high resolution XPS spectrum (Figure 3c) showed oxides peak Co2+ (780.0 eV), and Co3+ (782.1 eV). Therefore, the characterization successfully demonstrated the incorporation of various electrocatalytic active species in the encapsulated SURMOF. OER is an electrocatalytic water splitting reaction in which molecular oxygen produced by four electrons coupled mechanism in basic solution with a three-electrode system. The OER catalytic activity has been evaluated by linear sweep voltammetry (LSV) measurements from 0 to 0.8 V (Vs Ag/AgCl) in oxygen pre-saturated 1 M KOH solution with a scanning rate of 5 mV s-1. The corrected polarization curves are displayed in Figure 4a. The obtained LSV curves of the three different surface tuned SURMOF revealed different trends in OER activity. Remarkably, the Fe(Salen) surface tuned PIZA-1 exhibit best OER performance with the over potential of 340 mV (1.57 V Vs RHE) was required to achieve the current density of 10 mA cm-2 (Figure 4a). The result is comparable to the state-of-the-art RuO2 catalyst

46, 47

and

previous synthesized nanostructured derived thin film based OECs (Figure S12, Table S2).48-51 However, catalytic activity for remaining two surface modified thin films was displayed an increment in overpotential by 370 mV and 390 mV respectively at the same



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current limit. This can be explained as the balance between the numbers of the catalytic active sites decreases with the hydrophobic linkers increases, consistently decrease the catalytic behavior. Tuning the surface composition of electrocatalyst benefits in OER improvement because the synergistic effect of Fe to promote and stabilize -OOH intermediate species, eventually increases the extent of oxidation for Co to (Co(OH)2/CoOOH). Co(OH)2 + OH− → CoOOH + H2O + e−.28 Moreover, this allows for easier OH− intercalation and facilitates M–OOH which might be due to increased porosity/disorder in nanostructure thin film. DFT calculations have proposed that Fe3+ sites provide ideal binding energy for the −OH and −OOH.44 Secondly, TCPP ligand with hydrophobic nature of porphyrin prevents in reaching to the active catalytic centers in the diffusion of hydrophilic -OH molecules. Thus, the balance between

the

catalytic

active

sites

with

hydrophobic

structures

in

the

Fe(Salen)@PIZA-1-400[Fe] will afford to the best catalytic couple. Interestingly,

the

spinel-type

iron/cobalt

based

composite

thin

film

Fe(Salen)@PIZA-1-400 electrode in which Fe(Salen) complex in the top layer of the MOF exhibited better kinetic activity with a small Tafel slope of 56 mV dec-1 (Figure 4b) while Fe(Salen) and Fe(Salen)-400 samples with 120 and 112 mV dec-1 respectively. Tafel plot showed good linearity with small value will evident that Fe(Salen)@PIZA-1-400[Fe] was proved to be efficient OEC with a good electrical conductance for fast electron transfer. The Tafel plots were calculated by linear fitting of Log of J (mA cm-1) Vs. V from the LSV curve, which also gave an insight to the rate determining step in four electrons transfer OER mechanism, such as, Tafel slope close to 120, 40 and

28 mV dec-1 are estimated for

respective 1st 2nd and 3rd electron transfer steps are rate-limiting.52 Hence, all the three


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Fe(Salen)@PIZA-1-400[Fe], Fe(Salen)@PIZA-1-400[Co] and Fe(Salen)@PIZA-1-400[TCPP] thin film sample with 56, 70 and 79 mV dec-1 followed 1st electron transfer kinetics53, 54 followed by rate-determining chemical transformation. The tunable surface specie of the composite thin films for the OER studies showed that Fe(Salen)@PIZA-1[Fe] had the highest OER performance, which also demonstrated the presence of Fe3+species is an important factor for OER activity.

Figure 4. (a) Cyclic voltammograms of the Fe(Salen) and Fe(Salen) encapsulated PIZA-1 MOF modified FTO electrode after calcination at 400 oC in 1M KOH solution at a scan rate of 5 mVs-1 at room temperature; (b) Tafel curves (c) The Nyquist plot of Fe(Salen)@PIZA-1-400, Fe(Salen) and Fe(Salen)-400 electro catalysts; (d) LSV curve after



100

CV

cycles

and

inset

figure

shows

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chronoamperometric

curve

for

Fe(Salen)@PIZA-1-400[Fe]. For the good kinetic activity as well as for sustainable use of electro catalysts, chronoamperometric measurements were employed to test their stability and long-term durability (inset of Figure 4d) demonstrated that current density remains stable for 12 hrs. In addition to such high activity, Fe(Salen)@PIZA-1-400[Fe] nanocomposite thin film also displayed high stability as OER polarization curves of Fe(Salen)@PIZA-1-400[Fe] before and after 100 CV cycles (Figure 4d) showed no such noticeable degradation in OER activity, even after 100 cycles no decline was observed. Similarly, electrochemical impedance spectroscopy (EIS)

measurements

further

highlighted

the

good

kinetic

activity

of

the

Fe(Salen)@PIZA-1-400 with the smallest diameter of semi-circle value (58Ω, 79Ω, 115Ω) for respective modified thin film Fe(Salen)@PIZA-1-400[Fe], Fe(Salen)@PIZA-1-400[Co] and Fe(Salen)@PIZA-1-400[TCPP]. The OER charge transfer resistance (Figure 4c) followed a similar trend to the OER polarization curves Fe(Salen)@PIZA-1-400 which was also consistent with chronoamperometric responses. The

water

electrolysis

via

Fe(Salen)@PIZA-1-400

nanocomposite

thin

film

electro-catalyst was shown in Figure 4a. There were various factors which are performing a prominent role in such good OER performances, in which cobalt oxide (CoOx), Co-porphyrin and iron oxide (Fe2O3), graphitic carbon and nitrogen in the composite thin film nanostructures. Throughout the OER from water splitting predominantly forms M–OH, M–O, M–OOH, and M–O2 out of the various intermediates and finally ease the release of Oxygen gas M + O2 by means of the synergistic effect of heterometallic (Fe & Co) electro catalyst


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system. These results were comparable to most of the previous reports detailing the electro catalysis of water by related heterometallic thin film systems for oxygen evolution reaction.

Conclusion In conclusion, we have developed a Fe(Salen) compound encapsulated cobalt-porphyrin framework PIZA-1 (Fe(Salen)@PIZA-1) thin film with different surface compositions was successfully developed by using modified epitaxial layer-by-layer approach. After calcination at 400 oC, the composite Fe(Salen)@PIZA-1 derived film was used for oxygen evolution catalyst because of CoOx, Co-porphyrin and Fe2O3 and graphitic carbon was formed in the composite thin film. The electrochemical results showed that this unique modified material had a good catalytic activity for OER (η = 340 mV at 10 mA/cm2) and long-term stability. In addition, the OER activity can be optimized by tuning active specie on the surface of a thin film to porphyrin-based network. The results showed that Fe(Salen)@PIZA-1[Fe] had the highest OER performance, which can be attributed mainly that the large surface area, a high density and uniform distribution of orderly incorporation of bimetal active centers, balance between bimetallic active center to the porphyrin-based network. This design concept presented here will offer good understanding of the modified electro-catalyst

derived

from

encapsulated

MOF

films

based

material

in

electrochemical energy devices. ASSOCIATED CONTENT Supporting Information. Characterization details, additional figures and images; IR spectrometry; Raman and MS,

1

H-NMR spectrum are provided in the Supplemental



Information. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author * Corresponding Author e-mail: [email protected]

ACKNOWLEDGMENT The author S.M. expresses her gratitude to the CAS-TWAS President program, as it funded her PhD studies. This work was supported by NSFC (21872148 and 21601189), Youth Innovation Promotion Association CAS (2018339) and NSFC of Fujian province (2016J01085).

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For Table of Contents Use Only

Insight into Fe(Salen) Encapsulated Co-Porphyrin Framework Derived Thin Film for Efficient Oxygen Evolution Reaction Salma Mirza,†‡ Hao Chen,† Shu-Mei Chen,§ Zhi-Gang Gu†* and Jian Zhang† †

State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure

of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P.R. China. ‡

University of Chinese Academy of Sciences, Beijing, 100049, P.R. China.

§

College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, P.R. China

Table of Contents Graphic:

Synopsis: A Fe Salen compound Fe(Salen) encapsulated cobalt-porphyrin framework PIZA-1 (Fe(Salen)@PIZA-1) thin film with different surface composition was successfully developed by using modified epitaxial layer-by-layer approach and was studied for efficient oxygen evolution reaction.



A Fe Salen compound Fe(Salen) encapsulated cobalt-porphyrin framework PIZA-1 (Fe(Salen)@PIZA-1) thin film with different surface composition was successfully developed by using modified epitaxial layer-by-layer approach and was studied for efficient oxygen evolution reaction. 886x348mm (88 x 88 DPI)


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Insight into Fe(Salen) Encapsulated Co-Porphyrin Framework Derived

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