Electrodeposition of Inorganic, Organic and Hybrid Thin Films for Energy Conversion and Storage

Abstract

There are no winners nor losers in the fight against the global climate change. It is the fight
we cannot lose, in which all of us must become winners for our survival. The challenges for
carbon neutrality (CaN) by 2050 are now real and eminent.
Aside from the political challenges to avoid all the ridiculous international conflicts to hinder
the actions for CaN, near complete change of our energy system to renewable ones is the
most important technical challenge. It is not only about electrification of our life by renewable
sources such as solar and wind. Energy and resource saving technologies are important as
well. Also, because of the intermittency of renewable power, technologies for storing electricity
in a large-scale battery and ideally converting it into chemical fuels are needed.
We have been working on electrodeposition of functional thin films for the above-mentioned
purposes for over 1/4 centuries. Electrodeposition is a low-cost and scalable solution
processing of thin film materials. Starting from inorganic compound semiconductors such as
metal chalcogenides used in thin film solar cells [1], discovery of self-assembly of
nanostructured ZnO/organic dye hybrid thin film lead to an industry/university national project
for flexible dye-sensitized solar cells in 2000’s [2]. And by now, solar electricity from Si panels
became the cheapest, which was bitter for a researcher of organic solar cells, but welcome as
an individual, so that production of renewable electricity is no longer an issue but its storage
is highly important for on-demand use of renewable energy. We then shifted our research to
redox flow batteries as well as electrocatalysis for water splitting and CO2 reduction [3,4]. Once
again, electrodeposition plays an important role. The target now is a hydrogen-bonding
conductive organic polymer such as polydopamine that shows high catalytic activities for
hydrogen evolution and CO2 reduction reactions.
This way, our explorations have come to cover all kinds of materials to be electrodeposited.
In fact, it is not too useful to categorize materials as organic or inorganic, since history of the
synthesis remains in their properties. Variety of control parameters in the electrodeposition
process can result in fine-tuning of the products to suit the need in applications. Scientifically
understanding the phenomena of electrochemical precipitation is thereby the most important
for establishing a foundation for industrial development of electrodeposition.
In this talk, a review of the past/history of our research, the present and the future will be
discussed. Also, the foundation of Yamagata University Carbon Neutral (YUCaN) research
center to tackle the broader goals of carbon neutrality will be announced and explained.