(6dz) Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) Bifunctional Electrocatalyst Fabrication for Unitized Regenerative Fuel Cell (URFC) Application

Oxygen reduction
reaction (ORR) and oxygen evolution reaction (OER) bifunctional electrocatalyst fabrication for unitized regenerative fuel
cell (URFC) application

Pralay Gayen

Postdoctoral
research associate

Department
of Energy, Environmental and Chemical Engineering, Washington University in St.
Louis, St. Louis, MO

Research Objectives

            Environment
and energy are the pillars of human civilization which facilitates the
advancement of mankind. Water is one of the most vital ingredients for the
survival of human civilization on which the aforementioned pillars are based.
Energy and environment including water matrices are highly interconnected as
energy production from any source requires water and has environmental
consequences. Due to increase in energy consumption and decrease in fossil fuel
availability mankind is in urgent need to find sustainable energy equity that can
last for an extended time and of less environmental consequences. Water
pollution is one of the major complex problems in hand that needs to be
resolved by using next generation water treatment and sensing technique and require
expertise. To achieve sustainable energy with minimal environmental
consequences we need to introduce ecologically non-disruptive renewable energy
sources (solar and wind), carbon-free transportation sector, and find
alternative pathways for large scale fuel production. For our environment to sustain and be free from CO₂
related issues (e.g. air pollution, global warming etc.) we need to move
towards decarbonization, CO₂ sequestration
and CO₂ recycling. I will
holistically address these key challenges by leveraging my training and
expertise in highly efficient electrocatalyst
fabrication, thorough characterization and electrochemical application towards
water treatment, water sensing, fuel production via CO₂ recycling, energy
storage and conversion by developing next generation electrocatalyst
and electrochemical solution.

Postdoctoral Project
– “Highly
efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)
bifunctional electrocatalyst fabrication for fixed
gas unitized regenerative fuel cell (URFC) application”

Supervisor:
Prof. Vijay K. Ramani, Department of Energy, Environmental and Chemical Engineering,
Washington University in St. Louis (WUSTL)

PhD Thesis – “Surface
modification of electrode surfaces for water treatment and sensing applications”

Supervisor:
Dr. Brian P. Chaplin, Department of Chemical Engineering, University of
Illinois at Chicago (UIC)

M.Tech. Thesis – “Improving
efficiency of comminution in ball mills”

Supervisor:
Prof. Devang Khakhar,
Department of Chemical Engineering, Indian Institute of Technology Bombay
(IITB)

 Research Interests:

            During
my bachelor and masters study I worked on liquid-liquid dispersion and
comminution kinetics in a ball mill. During those projects I showed the effect
of different parameters for emulsion and dispersion formation. I also showed
the increase in grinding efficiency for mixture of particle size using mixed
ball size. Though the researches were based on fundamental science they aroused
my interest for cutting edge research.

            As
I always wanted to work on present challenges the world is facing I started
working on water treatment and sensing as a PhD student with Dr. Brian P.
Chaplin at UIC. The research experiences I gained are as follow: 1) development
of electrochemical sensors for the
determination of trace contaminants in natural water and wastewater effluent
matrix with high sensitivity and selectivity, 2) surface modification of
non-porous electrodes for the minimization of carcinogenic byproduct formation
with significant organic oxidation and subsequent removal from water and
wastewater matrices, 3) fabrication
of reactive electrochemical membrane (REM) using sub-stoichiometric TiO₂
with the incorporation of various oxide and bimetallic catalysts to achieve higher
organics and chemical warfare agents (CWAs) oxidation, inorganics reduction and
subsequent removal from water and wastewater matrices, and 4) synthesis of vertically
aligned multi-walled carbon nanotubes (VAMWCNT) using chemical vapor deposition
method, for the detection of trace contaminants in wastewater matrices with
excellent sensitivity and selectivity. Over
the course of these projects, I extensively utilized classical reaction
kinetics, electrochemical and analytical techniques.    

During my postdoctoral research project, I am working
mainly on the development of ORR/OER bifunctional catalyst for fixed gas
unitized regenerative fuel cell application. During the project I have been
applying my knowledge in electrocatalyst synthesis,
analytical characterization and electrochemistry towards highly efficient pyrochlore OER/ORR catalyst synthesis and their use in fuel
cell and electrolyzer application. The final
objective of this project is to create highly efficient URFC fabrication as a
coupled fuel and energy production device.

Future Research

            I will develop advanced electrocatalysts
with high activity and selectivity towards several applications such as
sustainable energy production and storage, advanced wastewater sensing and
treatment, fuel and specialty chemicals production.   

Project 1: Wastewater
treatment and sensing – Several conventional water treatment techniques
such as physical, biological, photochemical and chemical have been used for
water treatment applications for decades. However the most extensively used
physical separation techniques such as reverse osmosis, ion exchange, membrane
filtration etc. using polymeric membrane suffers from membrane fouling, high
energy usage, low flux, low operational lifetime, incomplete removal and
concentrated brine formation. Biological, chemical and photochemical methods
suffer from low removal efficiency, formation of byproducts, high cost due to
chemical addition, and UV light source requirement. Electrochemical
advanced oxidation process (EAOP) is emerging as an effective water and
wastewater treatment technology due to high current efficiency, low cost, no
requirement of chemical addition, absence of brine formation, and complete
contaminants removal. Thus,
I aim to circumvent the issue of low
current efficiencies, incomplete contaminant removal, concentrated brine
formation, high energy requirement, membrane fouling and high cost for water
treatment using conventional technique by adopting highly efficient, robust,
sustainable, low cost ceramic membrane and powerful electrochemical technique
combined with highly active electrocatalysts.

Different
analytical methods such as capillary electrophoresis, liquid
chromatography—mass spectroscopy, spectrophotometry, high performance liquid
chromatography (HPLC), immunoassay, chemiluminescence,
spectrofluorimetry and electrochemical techniques
have been extensively utilized for the detection of contaminants. Trace
contaminants detection and removal is of great importance because they are not
easily detected and treated using conventional techniques mentioned above. The
presence of trace contaminants (e.g. antibiotics, herbicides, heavy metals
etc.) pose serious hazard to human being as they cause the emergence of
drug-resistant bacteria, endocrine disruption, cancer etc.  Electrochemical techniques (impedance
spectroscopy, voltammetry, amperometry etc.) have
advantages over analytical techniques such as cost effectiveness, energetically
viability, robustness, high sensitivity, high selectivity, fastness and
easiness to use and emerged as suitable replacement for conventional techniques.
Thus, I aim to minimize
the issues of low sensitivity, large footprint, low selectivity, high energy
requirement, incomplete removal and low removal efficiency for conventional
technique by adopting highly sensitive, selective, low cost and powerful
electrochemical techniques combined with EAOP and electrochemical reduction
induced by electrocatalysts.

Project 2: Metal-air
battery - K-O₂ batteries have higher theoretical specific energy
densities compared to state-of-the-art Li-ion batteries and do not suffer from
poor energy efficiency. The discharge products of Li- and Na-O₂
batteries are the peroxides (Li₂O₂ and Na₂O₂)
whereas K-O₂
battery produces superoxide (KO₂) which
develops smaller charge overpotential. The low charge
overpotential increases the choice of material as
catalysts and electrolytes without risk of high voltage degradation. Thus, I aim to solve the issue of high overpotential
required to recharge Li-O₂ by using more facile alkali metal-air chemistries.
I also aim to further decrease the charge-discharge overpotential
of K-O₂ battery using ORR/OER
bifunctional catalyst.

Project 3: Fuel production
and energy conversion (URFC) -
Energy production from conventional fossil fuels suffers from severe pollution
and limited abundance. Sustainable energy and fuel production using fuel cell
and electrolyser have emerged as a suitable
alternative to the fossil fuels due to zero carbon emission and high abundance.
A URFC produces carbon-free hydrogen fuel via water oxidation under electrolyser mode and generates decoupled energy with rated
power under fuel cell mode using air/oxygen as oxidant. AEM URFC has gained
attention over PEM URFC in recent years due to low membrane cost, high choice
of catalyst, faster ORR kinetics and low degradation with high stability. For
the successful application of URFC, electrocatalysts
need to be bifunctional (e.g. ORR/OER, OER/HOR, ORR/HER etc.). Novel metal
catalysts are not cost effective and don’t show bifunctional activity as Pt/C
does not show OER activity due to oxide formation and subsequent passivation
whereas IrO₂ and RuO₂ show very poor ORR activity. I will
develop different non-noble metal electrodes such as pyrochlore
oxides, M-N-C, chalcogenides, metal oxides etc. as suitable substitute of
Pt-based electrodes which will lower the overall cost and mitigate the barrier
towards URFC application. Thus, to
achieve economically feasible, carbon-free, stable/reliable and sustainable energy
and fuel production I will use AEM URFCs by developing highly active non-PGM novel
bifunctional catalysts.

Project 4: H₂
production via sea water electrolysis – Due to less abundance and
environmental impact of energy production via fossil fuel combustion human
civilization is in urgent need of finding alternatives. Hydrogen could be a
suitable alternative due to its high energy density (120-142 MJ/kg) and absence
of carbon footprint. About 96.5 % of earth’s water is ocean water and could be
a great source for hydrogen and oxygen via electrochemical water splitting. The
application of OER with sea water is limited due to the parasitic chlorine
evolution reaction via Cl^- oxidation. However, CER is suppressed with increase in pH
with the formation of other chlorine-containing species like chlorite,
hypochlorite or chlorate. The chlorate salts exhibit low solubility in aqueous
conditions and its deposition on electrocatalysts
leading to long-term stability and catalyst poisoning issues. Therefore, to achieve cost effective H₂
production with excellent activity and stability using SWE I will develop highly
active, OER selective, and stable catalyst and stable AEMs for the development
of highly active sea water electrolyzer.

Project 5: Electrocatalytic value added
chemical production –

CO₂
recycling and conversion - The major source of energy till date is via fossil
fuel combustion which produces excessive amount of CO₂, a greenhouse
gas. The accumulation of CO₂ in the earth environment is responsible
for serious problems related to climate change which needs to be resolved in
urgent manner. Due to slow progress of renewables and the presence of
industrial CO₂ emission carbon recycling is an effective pathway necessary
to lower the CO₂ burden on earth. Carbon-based high energy density fuels
(e.g. methane, ethanol, ethylene, methanol etc.) production is also necessary
as they have been used for different purposes and have higher volumetric energy
density compared to hydrogen. Thermal CO₂ reduction/hydrogenation to
form carbon-based fuels using high temperature and pressure is widely used for
carbon recycling via reverse water gas shift, methanation
and Fischer-Tropsch reaction. CO₂electroreduction (CDER) has certain advantages over
conventional thermal hydrogenation such as single process combining
hydrogen formation with high product selectivity and operation ability under
ambient condition. The application of Cu, a conventional catalyst has been
hindered due to its high overpotential and inability
to form economically feasible and high energy density products such as ethanol
and methanol. Therefore, to achieve highly
selective alcohol production via CDER with excellent activity and
stability in a batch system I will develop highly active, alcohol selective and
stable catalyst. To make CDER more robust and cost effective I will develop electrolyzer with OER anodic reaction and CDER cathodic
reaction that will produce oxygen and value added fuels for further use.

Ammonia
production – Ammonia has been
produced via conventional energy intensive Haber-Bosch process with large CO₂
footprint and high amount of H2 requirement. Electrocatalytic
ammonia production will have certain advantages such as low CO₂
production, less energy intensive and distributed production at the application
site. The advantages are multiplied for electrocatalytic
ammonia production as H₂ has been produced in-situ via water reduction.
I will develop bimetallic, metal oxide, carbide, nitride and organic catalysts
for electrochemical ammonia synthesis from water and air with ambient condition.
Combining DFT screening of catalysts and with experimental data I will down
select the highly active catalysts to evaluate their nitrogen reduction
kinetics, and optimize larger-scale to produce ammonia in bulk.      

Teaching Interests:

            During
my teaching assistantship of total 10 courses including 8 lab core courses and
2 teaching core course of chemical engineering I have amassed experiences and
knowledges which will assist me to serve as an instructor for teaching the
traditional core chemical engineering courses. During my M. Tech. program I
served as a teaching assistant for 4 undergraduate lab courses regarding
process control and electroplating. During my PhD program, I served as a teaching
assistant for 5 core chemical engineering courses including transport phenomena
and undergraduate labs. Due to my teaching assistantship in several lab courses
I have realized and observed that students have gathered better understanding
and experiences via lab experiments. During my teaching assistantship I have
instructed the courses, demonstrated the experiments to the class, solved
instrumental challenges, checked the lab reports and uploaded the grades in
University of Illinois at Chicago (UIC) blackboard. The experiences of
assisting in the teaching of undergraduate level transport phenomena provided
invaluable insights into the shades of balancing profundity and clarity without
sacrificing technical accuracy. During my postdoctoral program, I have also
served as assistant to instructor for Energy Conversion and Storage at
Washington University in St. Louis (WUSTL), where I have been responsible for
class planning, preparing exam papers, and grading the answer sheets. As part
of this course, I helped also in developing the lab modules consisting fuel
cell, electrolyzer, and battery experiments along
with their lab manuals, standard operating procedure (SOP) and instructional
materials. During this course I have observed an excellent combination of
theoretical and experimental study which implemented deep knowledge and better
understanding of the subject into the students. My long background in chemical
engineering has prepared me to serve as an instructor for any of the ChE core courses at all levels. I look forward to bringing
this passion to my future role as a ChE faculty member.

Selected Publications (5 published and 5 under preparation)

1.    
Gayen,
P., Chen, C., Abiade, J. T., & Chaplin, B. P.
(2018). Electrochemical Oxidation of Atrazine and Clothianidin
on Bi-doped SnO₂–Ti_nO_2n–1Electrocatalytic
Reactive Electrochemical Membranes. Environmental science &
technology, 52(21), 12675-12684.

2.    
Gayen,
P., Spataro, J., Avasarala,
S., Ali, A. M., Cerrato, J. M., & Chaplin, B. P. (2018). Electrocatalytic Reduction of Nitrate Using Magnéli Phase TiO2 Reactive Electrochemical Membranes
Doped with Pd-Based Catalysts. Environmental
science & technology, 52(16), 9370-9379.

3.    
Gayen,
P., & Chaplin, B. P. (2017). Fluorination of boron-doped diamond film
electrodes for minimization of perchlorate formation. ACS applied
materials & interfaces, 9(33), 27638-27648.

4.    
Gayen, Pralay, and Brian P. Chaplin. "Selective electrochemical
detection of ciprofloxacin with a porous nafion/multiwalled carbon nanotube composite film
electrode." ACS applied materials & interfaces 8.3
(2016): 1615-1626.

5.    
Jawando, W., Gayen, P., & Chaplin, B.
P. (2015). The effects of surface oxidation and fluorination of boron-doped
diamond anodes on perchlorate formation and organic compound oxidation. Electrochimica Acta, 174,
1067-1078.