Recent progress for reversible homogeneous catalytic hydrogen storage in formic acid and in methanol

Development of technologies using hydrogen as an energy carrier instead of fossil fuels is strongly required today. Especially, new, reversible, sustainable hydrogen storage technologies have received increasing attention. Formic acid (FA) and methanol (CH3OH) are considered as effective liquid chemicals for hydrogen storage as being easier to handle than solid or gas materials. This review summarizes the recent progress of research on the development of homogeneous catalysts mainly focusing on FA and CH3OH and the reports on the complexes based on both precious and non-precious metals which are rapidly increasing in the past few years.