The Esposito Research Group at Columbia University was highlighted in the February 2019 newsletter put together by the International Association for Hydrogen Energy (IAHE). The IAHE is an organization that promotes hydrogen as a key energy carrier in a sustainable energy future by organizing H2-oriented scientific conferences, running a peer-reviewed journal (International Journal of Hydrogen Energy), and coordinating a number of other activities that generally support the spread of information on hydrogen-related technology.  H2-enthusiasts can become members of the IAHE through their website, and students can join for free to receive the IAHE E-newsletter by emailing John Sheffield at john.sheffield@dnvkema.com for more information.

The full February 2019 IAHE newsletter can be found here, with the feature highlighting the Esposito Research Group (pgs. 31-33) is copied below:


Research Lab Highlight

Esposito Research Group, Columbia University
The following is a Q&A interview with Professor Daniel Esposito, the group’s director.
By: Anirban Roy
Q. Tell us a little about your research group and the work you focus on?
A. Our group is comprised of a very talented mix of Ph.D.,
postdoc, MS, and undergraduate researchers, and our research
interests relate broadly to electrochemical technologies
that are able to convert sunlight or solar-derived
electricity into storable fuels and chemicals. We are
based in the Department of Chemical Engineering at Columbia,
and are core members of the newly formed Columbia
Electrochemical Energy Center (CEEC). The majority
of our research focuses on developing electrocatalytic
materials and devices for electrolysis and fuel cell technologies.
These efforts are strongly complemented by advanced
analytical tools, such as scanning electrochemical
microscopy (SECM) and in situ high speed video, which
allow us to probe the properties and performance of electrode
materials with high spatial and/or temporal resolution
(see more below). Research projects in our lab are
funded by a mix of government and industry sponsors,
and address a wide range of questions spanning basic
science to application-driven design problems. Presently,
major ongoing research projects in our group include the
development of i.) encapsulated electrocatalysts and ii.)
membraneless electrochemical cells, both of which offer
exciting opportunities to impart new functionalities in
electrolyzers and fuel cells that are not possible with conventional
electrocatalysts and devices.
Q. What is your research methodology?
A. An important part of my research methodology is how
I choose the problems I work on. One of the things that
most strongly motivates my group’s research is the possibility
of developing a new material or device that can lead
to transformative impacts on our energy system. The climate
challenges society faces are real and urgent, and
incremental improvements in clean energy technologies
are not going to be enough. Thus, when I come up with a

new project idea to pursue, I always ask myself if that idea
has a chance to directly or indirectly lead to a step change
in one or more key performance metric (s). If not, I generally
shy away from pursuing it further. Naturally, this
leads one to pursue unconventional ideas that have lower
chances of “success” (in the traditional sense), but creates
a greater chance of discovering something that has real
potential to significantly extend our knowledge envelop
and lead to game changing technology. To explore high-risk
ideas, or any advanced/complicated research question
for that matter, I like to start simple and build up in
complexity. Thus, we do a lot of work with model electrode
surfaces and “as simple as possible” devices that
can allow us to better understand the fundamental physics
and chemistry that underlies their operation, and more
quickly get to the point to where we can test key hypotheses/
ideas. Concurrently, I think it is essential to address
difficult research problems with cutting edge experimental
and computational capabilities. For this reason, we
put a lot of effort into developing new in situ analytical
tools and methodologies (see more below), and actively
collaborate with others who are experts in techniques and
methods that are complementary to our own.

Q. There has been a recent trend in scientific research to
perform “in-situ” experiments. What are your thoughts on
“in-situ” techniques?
A. We’re big proponent of using in situ techniques to
study electrochemical materials and devices whenever it is
reasonable to do so. Whether we are talking about a
spectroscopy, imaging, or electrical measurement, we almost
always prefer in situ measurements over ex situ
measurements, and we want that tool to give us as much
information as possible. The computational capabilities of
our colleagues who specialize in modelling/theory are improving
at a rapid rate, and we experimentalists need to
keep up! When studying electrode materials, in situ measurements
are capable of providing invaluable insights
about material properties/characteristics that can be very
different from those observed for the same material when
measured outside of the electrochemical environment.
When studying electrochemical devices, in situ imaging
techniques with high spatial and/or temporal resolution
offer the ability to gather rich data sets that can be of
great value for i.) validating models, ii.) diagnosing issues,
and iii.) guiding the design of optimal geometries.

All of that being said, in situ measurements often pose
significant challenges to carry out successfully, and are
not for the faint of heart! The design and construction of
new in situ experimental capabilities often require substantial
time/cost/blood/sweat/tears, and the measurements
themselves might ultimately be a step removed
from the operating conditions of a real electrolyzer or fuel
cell. However, the potential payoff for these efforts are
huge, especially if they can help create a link to emerging
computational technologies with the ability to accelerate
the design and prediction of materials/devices.
Q. Your thoughts on hydrogen as viable future resource
energy carrier?
A. I have tremendous optimism for the role that hydrogen
(H2) will play as an energy carrier in a sustainable energy
future. Much of this stems from the ability to obtain clean
H2 fuel at large scale using renewable energy by water
electrolysis in the absence of any CO2 emissions (or any
carbon at all). The other feature that makes H2 so attractive,
in my mind, is its versatility as a fuel and chemical
that can be used by almost every energy sector. We as a
society rely extensively on fuels today due to their many
desirable properties (high energy density, negligible “self-discharge”,
application at large scale) and I am confident
in saying that fuels will continue to play an important role
in a future sustainable energy system. I believe that H2,
both as a fuel itself, and as an intermediate used to upgrade
CO2 into liquid hydrocarbon fuels, will be the foundation
of that future fuel mix.
Q. What are the key research areas that need to be addressed
for a feasible Hydrogen economy? (Also mention
your contributions)
A. H2 economy only makes sense in the long run if the
vast majority of that H2 is “green hydrogen” that is produced
without any associated greenhouse gas emissions.
Preferably, that hydrogen is produced by water electrolysis
using renewable electricity, in which case carbon is
completely removed from the equation. We have commercially
available technology for producing, storing, and
using hydrogen produced from water electrolysis in a safe
and scalable manner. The biggest barrier to widespread
implementation of these technologies is the cost of hydrogen
energy compared to fossil fuels like natural gas and oil.

Fortunately, the falling prices of electricity from solar photovoltaics
and wind are making the economics of H2 production
from water electrolysis more favourable. However,
low-price electricity (0.02 $/kWh) will not be enough to
tip the balance in favor of H2. Additionally, it will be essential
that the capital costs of electrolyzers and H2 storage
technologies be brought down to levels that are substantially
below where they are today. This is especially
important in a renewable energy future when low-price
electricity becomes commonplace, but only for a small
fraction of the day. This realization was a key motivating
factor behind my group’s work with membraneless electrolyzers,
which possess very different architectures and
operating principles from conventional PEM and alkaline
electrolyzers. These membrane free devices have potential
for low-cost manufacture (see more below) as well as durable
operation in harsh environments where conventional
cells would not be stable due to fouling or blocking of
the membrane or divider. In my opinion, developing materials
and device architectures that can have longer lifetimes
and be more robust in the presence of impurities
will be of great importance, and requires a lot of additional
research efforts. Towards this end, my lab also has substantial
effort to develop electrocatalyst materials that are
encapsulated by ultrathin permeable overlayers that can
help to mitigate nanoparticle coalescence/detachment, as
well as block impurities or unwanted reactants from
reaching the catalytically buried interface. Beyond efforts
to develop more durable/tuneable electrocatalysts and
low-cost devices, I think it will also be important for researchers
to make progress on developing low-cost nonprecious
metal electrocatalysts without compromising on efficiency.
Q. What were your inspirations behind the 3D printed
membraneless electrolyser, and the concept of a solar PV
coupled floating electrolyser?
A. The earliest inspiration for the membraneless electrolyzers
we work on in my lab came from reading articles on
membraneless laminar flow fuel cells and flow batteries
developed by Paul Kenis’s lab at Illinois, with later work by
Martin Bazant’s lab at MIT. I was struck by the simplicity
of those device architectures, and the ability to use fluid
flow to achieve efficient separation of electrochemically
generated products in the absence of any membranes.
However, those cells were relatively small-scale microflu-

idic devices. About 5-6 years ago I came across an image
in a National Geographic article (that had absolutely
nothing to do with electrochemistry or hydrogen!) of a
porous material, which lead me to think about ways that
porous flow-through electrodes might be used in scalable
membraneless electrolyzer architectures. Fast forward to
today, and the electrodes/devices that we are currently
working on are almost unrecognisable from some of the
first sketches that I and my students came up with.
As mentioned above, we are interested in exploring membraneless
electrolyzers as robust devices that can reduce
capital costs far below those of conventional cells that are
built around membranes/dividers. Membraneless electrolyzers
offer an avenue to achieve this goal by reducing the
number of device components and the cost of manufacturing/
assembly. The floating membraneless PV-electrolyzer
concept was an extension of this logic. After
getting rid of the membrane and the pump, we decided
to simplify the system even further by integrating the PV
and electrolyzer while simultaneously removing the need
for solid ground for the technology to operate on.
Around 70% of the earth’s surface is covered by water;
why not use a tiny fraction of it for energy harvesting? It
is fun to think about a future floating “solar fuels rig” operation
that uses abundant and cheap solar energy and
seawater to generate H2 at large scale. Others in the solar
fuels field have thought about this concept before as well,
but we were, to the best of my knowledge, the first to
demonstrate a standalone, floating PV electrolyzer. That
work was based on a relatively small prototype, and there
are many significant challenges associated with producing
H2 from seawater, but we hope that demonstration might
provide inspiration for other groups to help us move the
concept closer to reality.
Q. What is your advice for the young generation, who are
willing to contribute to science, engineering and a better
sustainable society?
A. In order to achieve a sustainable energy future, we
need “all hands on deck”. Climate change is one of the
grand challenges of our time, and it is critical that we
have our best and brightest young minds go into science
technology engineering and math (STEM) fields with the
goal of developing clean energy technologies that will
help to mitigate the effects of climate change. There

could not be a more important time to enter into this field
and make a difference. Additionally, I would encourage
students to exercise their creative thinking muscles whenever
possible in order to better develop into the innovators
that we need. I suggest that students and young
professionals alike try to reserve a half day a week to let
their minds wander away from structured course work
and “normal” research plans to brain storm new ideas.
Unfortunately, incremental changes in today’s clean energy
technologies are not going to be sufficient to reverse
the trend in CO2 emissions as quickly as we need them to.
Innovative new ideas that lead to step changes in the economics
of these technologies are a must, and I have no
doubt that this generation of young scientists will develop
those technologies if they can realize their creative potential.