Catalytic reactions with ion transfer through interfaces have been a dynamic research topic for a long time both in catalysis and chemical reaction engineering. In recent several decades, the knowledge accumulated on such topics has facilitated the fast development of energy transformation and storage technologies. In many applications, e.g., proton exchange membrane fuel cells, lithium-batteries, membrane and photo-catalytic reactors for chemical production and pollutant abatement, reactions with ion transfer have already become the core of the technologies in fast commercial penetration. In recent years, we are also experiencing fast, exciting and potentially high impact progresses on such topics as water splitting cells, solid oxide fuel cells, new concept batteries and supercapacitors.
With the encouragement of the organizing committee of the EuropaCat2019, colleagues at Aalto University initiated this workshop in 2019 as a pre-conference of the main conference. The first workshop was very successful (see https://www.aalto.fi/en/iticat2019, and https://doi.org/10.1016/j.cattod.2021.01.002 ), but due to the pandemic, both the EuropaCat and its preconference has to be postponed to 2023 after the 2019 gathering. The purpose of the 2^nd workshop is still to offer a forum to present the new breakthroughs and to exchange the fundamental understandings on the steps and kinetics of such catalytic reactions. The organizers especially encourage communications on the design principles of the reactors for such reactions, i.e., those with ion transfer through interfaces.
August is the best season of Helsinki metropolitan area in Finland, offering a beautiful maritime scenery, world-renowned architectural designs as well as a bustling city scene. Helsinki is also the best place for the linkage of different continents with frequent connects globally. Dipoli building, the conference venue, is a fine representative of Finnish architecture and locates in the university’s Otaniemi campus in the city of Espoo, which is the most sustainable city of Europe. From Dipoli, it takes about 15 min to reach Helsinki city center by metro or taxi. 
Colleagues in the organizing committee, working on the principles and processes of energy transformation and storage, would like to extend their warmest hospitality to host colleagues coming from all over the world.  In this way, we also make our contribution to the success of the EuropaCat 2023.
On behalf of all the organizers, I would appreciate greatly your coming and contribution to the 2^nd workshop on “Catalytic Reactions with Ion Transfer through Interfaces”.