Flavin-inspired as electrocatalysts towards more sustainable hydrogen production

abstrakt

angličtina

The global need for energy has significantly risen in recent decades and is supplied mostly by fossil fuels which account for around 80 % total energy demands. Therefore, renewable sources of energy have been pointed in the centre of interest. Among them, hydrogen economy can address the utmost need for a transition to the green energy. To date, however, vast majority of hydrogen is produced by steam-methane reforming. On the other hand, low-emission production comprised less than 1% in 2022. Low emission hydrogen production can be achieved by electrolysis of water with overall equation 2H2O → 2H2 + O2, driven by renewable electricity sources. Being kinetically sluggish, the electrocatalytic HER is often mediated by catalysts. Massive upscale of effective electrolytic water splitting should be promoted by materials with low socioecological footprint which can be addressed by sustainable and recyclable organic electrocatalysts. Increasingly, bio-inspired organic materials emerge as robust and stable electrocatalysts with fine-tunable structure and properties (e.g. emeraldine-polyguanine or polydopamine, mimicking platinum surface).1 Flavins are ubiquitous cofactors of enzymatic redox reactions involving transfer of one or two electrons occurring over wide potential range which translated also in numerous applications. Riboflavin and its electropolymerized form coated on a carbon electrode serve as excellent electron shuttles promoting electron uptake in microbial fuel cells. Moreover, polyriboflavin proved to be active in oxygen evolution reaction.2 Redox-active part of riboflavin can be minimized to pteridine-2,4-dione moiety important for preserving the diazabutadiene moiety. On the other hand, expansion of the conjugated system is desirable for tuning of the optical and electrochemical properties.3 We present a versatile synthetic approach towards advanced non-fused NH-free flavin derivatives and their initial evaluation as electrocatalysts for hydrogen evolution. Both small-molecular and polymer materials were synthesized and investigated via electrochemical measurements followed by electrolytic experiments. Electrocatalytic activity of some metal-free flavin materials was observed in terms of several fold increase in amount of evolved hydrogen. Versatility of the synthesis of flavin-based small molecules and corresponding polymers enables enlarging of the portfolio of the catalysts for deeper experiments and potential applications in HER.

electrocatalysts, flavins, hydrogen evoljution

RICHTÁR, J.; IVANOVÁ, L.; KRAJČOVIČ, J.

JKU Linz

Kirchberg in Tirol

99

99

114