Subscriber access provided by EDINBURGH UNIVERSITY LIBRARY | @ http://www.lib.ed.ac.uk
Applications of Polymer, Composite, and Coating Materials
Efficacious Electrochemical Oxygen Evolution from Novel Co (II) Porphyrin-Pyrene based Conjugated Microporous Polymer Subhajit Bhunia, Kousik Bhunia, Bidhan Chandra Patra, Sabuj Kanti Das, Debabrata Pradhan, Asim Bhaumik, Anirban Pradhan, and Santanu Bhattacharya ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b20142 • Publication Date (Web): 14 Dec 2018 Downloaded from http://pubs.acs.org on December 15, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 31 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
ACS Applied Materials & Interfaces
Efficacious Electrochemical Oxygen Evolution from Novel Co (II) Porphyrin-Pyrene based Conjugated Microporous Polymer Subhajit Bhunia,† Kousik Bhunia,‡ Bidhan Chandra Patra, † Sabuj Kanti Das,§ Debabrata Pradhan,‡ Asim Bhaumik, *§ Anirban Pradhan, *† Santanu Bhattacharya. *† †School
of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of
Science, Jadavpur, Kolkata - 700032, India. E-mail id.-
[email protected] (Prof. S. Bhattacharya), E-mail
[email protected] (Dr. A. Pradhan), §
School of Materials Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata- 700032, India. E-mail id.-
[email protected] (Prof. A. Bhaumik) ‡Materials
Science Centre, Indian Institute of Technology (IIT) Kharagpur-721302, India.
ACS Paragon Plus Environment
1
ACS Applied Materials & Interfaces 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
Page 2 of 31
ABSTRACT:
Oxygen evolution reaction (OER) is energetically challenging from the platform of making many photovoltaic devices such as metal-Air battery and water splitting systems, because of its poor kinetics even when precious metals are used. Herein a Co (II)–porphyrin/pyrene comprised conjugated microporous polymer Co-MPPy-1 has been developed which shows efficient oxygen evolution reaction in alkaline medium. The material was characterized by FT-IR, solid-state 13C CP-MAS NMR, N2 volumetric adsorption/desorption analysis, SEM, UHR-TEM, XPS, and other physical studies. Co-MPPy-1 showed Brunauer− Emmett−Teller (BET) surface area of ~ 501 m2 g−1. Co-MPPy-1 achieved a current density of 1 mA cm-2 and 10 mA cm-2 at 340 mV and 420 mV respectively. The turnover frequency (TOF) calculated for the OER is 0.43 sec-1. The heterogeneity of this electrocatalyst was tested by chronoamperometric measurement and 1000 cycle recyclability test with retainment of the excellent electrochemical catalytic activity. This can be attributed to the presence of high density of Co (II) porphyrin unit and efficient charge transport in the π-conductive conjugated polymeric backbone.
KEYWORDS: Donor-acceptor, Pyrene-porphyrin, Noble metal free, oxygen evolution reaction, microporous
INTRODUCTION Transformation of small molecules e.g. H2O, CO2 etc. by means of the photochemical or electrochemical process is a promising avenue in the renewable, sustainable energy platform.1 The concept of water splitting into hydrogen and oxygen and their recombination to give water molecule is one of the demanding energy transformations
ACS Paragon Plus Environment
2
Page 3 of 31 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
ACS Applied Materials & Interfaces
which hold a promising approach to the sustainable energy issue.2 Oxidative oxygen evolution reaction (OER) is sluggish than reductive hydrogen evolution reaction (HER) in the water-splitting process.3-4The complicated reaction pathway involving multielectron/protons (4e-/4H+) transformation, higher over-potential etc. make the OER process indolent. Electron-rich noble metals are the most appropriate candidates than redox-active transition metals to execute this multi-electron process. RuO2 and IrO2 are known to be among the most effective oxygen evolution catalysts (OEC) till now.5But the manufacturing cost, low availability etc. make the entire process impractical. The development of cost-effective as well as efficient electro-catalyst is indeed a very challenging task and it is highly beneficial to increase the OER activity and current density at low over-potential value. Several combinational methods had been tried in order to increase the conductivity and catalytic activity for the development of a highperformance OEC. By combining amorphous carbon (C),6 graphene (G),7-8
carbon
nanotube (CNT)9 with transition metal oxides, various OER catalysts have been designed. Panet et al. had synthesized carbon, oxygen, and titanium-containing OER electrocatalyst using a unique protocol.10 However mixed binary, ternary, quaternary metal oxides are proven as powerful water oxidation catalyst so far.11 Recently insertion of metal ions (Co 2+,
Ni
2+,
Fe
2+
etc.) in the organic co-ordination environment has been shown as another
strategy to develop OER electrocatalysts. Kern et al. designed Co(II)-porphyrin functionalized bimetallic metal-organic framework (MOF) for OEC.12 Wang et. al. have shown chelated Co2+ as an active site in the S,N,O atom doped graphene.13 The discovery of conjugated microporous polymer (CMP),14-16 gained a huge point of interest regarding the electronic and photophysical phenomena. CMPs have proven themselves as an
ACS Paragon Plus Environment
3
ACS Applied Materials & Interfaces 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
Page 4 of 31
efficient and competitive candidate with crystalline MOFs and COFs towards many applications such as gas storage,17-19 sensing,20-22 catalysis,23-27 charge-carrier mobility,2830
and supercapacitor,31-33 etc. In addition, CMPs are ideal from the viewpoint of chemical
stability and robustness. However, the π-conjugated CMP, immobilizing with the molecular electroactive unit by choosing appropriate functionality and synthetic strategy which can be exploited for the targeted electro-chemical conversion.34-35 Recently several methods have been developed for the immobilization of electro-active moiety within the metal-organic framework,36-38 or covalent organic frameworks.39-41 For most of the cases, thermal annealing of MOFs, CMPs are necessary to execute electrochemical reactions (OER, ORR, HER). Because the thermal annealing leads to the graphitic conversion of such materials42-46 which make the system intrinsically conductive along with the electrocatalytic site. This type of pyrolytic porous electro-catalysts suffers from a lack of interest due to their manufacturing cost due to the expensive methodology. In contrast, as synthesized pure CMP, COFs are hardly examined for showing efficient electrochemical oxygen evolution reaction. In the present work we have synthesized a metal organic conjugated microporous polymer designated as Co-MPPy-1 via solution phase Suzuki cross-coupling reaction (Figure 1), in which the pyrene-porphyrin comprised donoracceptor based conjugated polymeric bilayer heterojunction (Co-MPPy-1) having active cobalt (II) site followed excellent kinetics toward electrochemical oxygen evolution from alkaline aqueous medium without any requirement of thermal activation.
ACS Paragon Plus Environment
4
Page 5 of 31 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
ACS Applied Materials & Interfaces
EXPERIMENTAL Chemicals Pyrene (98%, Sigma Aldrich), bis(pinacolato)diboron (98%, spectrochem, India), Pd(PPh3)4
(99%,
spectrochem,
India),
pyrrole
(98%
Sigma
Aldrich),
p-
bromobenzaldehyde (98%, spectrochem, India), meso-Tetraphenylporphyrin (
