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Updated: May 23, 2026

Hydrogen Production and Utilization in a Membrane Reactor
Published on: March 10, 2023
Reversible hydrogen storage using CO2 and a proton-switchable iridium catalyst in aqueous media under mild
Jonathan F Hull1, Yuichiro Himeda, Wan-Hui Wang
1Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA. hull@bnl.gov
Abstract:
Green plants convert CO(2) to sugar for energy storage via photosynthesis. We report a novel catalyst that uses CO(2) and hydrogen to store energy in formic acid. Using a homogeneous iridium catalyst with a proton-responsive ligand, we show the first reversible and recyclable hydrogen storage system that operates under mild conditions using CO(2), formate and formic acid. This system is energy-efficient and green because it operates near ambient conditions, uses water as a solvent, produces high-pressure CO-free hydrogen, and uses pH to control hydrogen production or consumption. The extraordinary and switchable catalytic activity is attributed to the multifunctional ligand, which acts as a proton-relay and strong π-donor, and is rationalized by theoretical and experimental studies.
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