Eun Jin Son

Enzymatic photosynthesis of formate from carbon dioxide coupled with highly efficient photoelectrochemical regeneration of nicotinamide cofactors

We present the photoelectrochemical (PEC) regeneration of nicotinamide cofactors (NADH) coupled with the enzymatic synthesis of formate from CO2 towards mimicking natural photosynthesis. The water oxidation-driven PEC platform exhibited high yield and the rate of NADH regeneration was compared to many other homogeneous, photochemical systems. We successfully coupled solar-assisted NADH reduction with enzymatic CO2 reduction to formate under continuous CO2 injection.

Nature-inspired Synthesis of Nanostructured Electrocatalysts through Mineralization of Calcium Carbonate

Biomineralization is a biogenic process that produces elaborate inorganic and organic hybrid materials in nature. Inspired by the natural process, this study explored a new mineralization approach to create nanostructured CaCO3 films composed of amorphous CaCO3 hemispheres by using catechol-rich polydopamine (PDA) as a biomimetic mediator. The thus synthesized biomimetic CaCO3 was successfully transformed to nanostructured films of metal-oxide minerals, such as FeOOH, CoCO3 , NiCO3 , and MnOOH, through a simple procedure. The CaCO3 -templated metal-oxide minerals functioned as efficient electrocatalysts; a CaCO3 -templated cobalt phosphate (nanoCoPi) film exhibited high stability as a water-oxidation electrocatalyst with a current density of 1.5 mA cm-2 . The nanostructure of nanoCoPi, consisting of individual nanoparticles (≈70 nm) and numerous internal pores (BET surface area: 3.17 m2  g-1 ), facilitated an additional charge-transfer pathway from the electrode to individual active sites of the catalyst. This work demonstrates a plausible strategy for facile and green synthesis of nanostructured electrocatalysts through biomimetic CaCO3 mineralization.

Unbiased biocatalytic solar-to-chemical conversion by FeOOH/BiVO 4 /perovskite tandem structure

Redox enzymes catalyze fascinating chemical reactions with excellent regio- and stereo-specificity. Nicotinamide adenine dinucleotide cofactor is essential in numerous redox biocatalytic reactions and needs to be regenerated because it is consumed as an equivalent during the enzymatic turnover. Here we report on unbiased photoelectrochemical tandem assembly of a photoanode (FeOOH/BiVO4) and a perovskite photovoltaic to provide sufficient potential for cofactor-dependent biocatalytic reactions. We obtain a high faradaic efficiency of 96.2% and an initial conversion rate of 2.4 mM h−1 without an external applied bias for the photoelectrochemical enzymatic conversion of α-ketoglutarate to l-glutamate via l-glutamate dehydrogenase. In addition, we achieve a total turnover number and a turnover frequency of the enzyme of 108,800 and 6200 h−1, respectively, demonstrating that the tandem configuration facilitates redox biocatalysis using light as the only energy source.Photoelectrochemical (PEC) cell platforms typically need an electrical bias that drives the electron transfer from the photoanode to the photocathode. Here, the authors report a bias-free PEC tandem device for solar-driven redox biocatalysis.