Photoelectrochemical Reduction of Carbon Dioxide to Methanol through a Highly Efficient Enzyme Cascade

Abstract

Natural photosynthesis is an effective route for the clean and sustainable conversion of CO2 into high‐energy chemicals. Inspired by the natural process, a tandem photoelectrochemical (PEC) cell with an integrated enzyme‐cascade (TPIEC) system was designed, which transfers photogenerated electrons to a multienzyme cascade for the biocatalyzed reduction of CO2 to methanol. A hematite photoanode and a bismuth ferrite photocathode were applied to fabricate the iron oxide based tandem PEC cell for visible‐light‐assisted regeneration of the nicotinamide cofactor (NADH). The cell utilized water as an electron donor and spontaneously regenerated NADH. To complete the TPIEC system, a superior three‐dehydrogenase cascade system was employed in the cathodic part of the PEC cell. Under applied bias, the TPIEC system achieved a high methanol conversion output of 220 μm h−1, 1280 μmol g−1 h−1 using readily available solar energy and water.

Interfacing nature’s catalytic machinery with synthetic materials for semi-artificial photosynthesis

“…Approaching the complex metabolic pathways of microorganisms, a solution-based enzyme cascade was established through the reduction of NADP + with a silicon photocathode, and utilizing the reducing equivalent of NADPH to drive CO 2  HCOOH  H 2 CO  CH 3 OH via solubilized FDH, formaldehyde dehydrogenase (FADH), and alcohol dehydrogenase (ADH), respectively (Fig. 4b) 102 . While still not competitive in terms of pure photocurrent yields (~40 uA cm −2 at zero-bias for NADH regeneration), precisely designed catalytic cascades that generate multiply reduced CO 2 -derived products are a unique feature of enzymatic photocathodes and serve as inspiration for their synthetic counterparts aiming to generate a more complex array of products.…”

“…4 -Semi-artificial photocathodes. Photoelectrochemical reactions via single enzymes adsorbed onto a nano-engineered TiO 2 surface (a) 40,98,99 , enzyme cascades in solution (b) 102 , and metabolic pathways of acetogenic microorganisms grown on silicon nanowire electrodes (c) 106 result in products with increasing levels of complexity. Increasing degrees of complexity lead to higher value chemicals through controlled multiple electron reduction of the substrate, albeit with a loss of control over interfacing and charge direction.…”

Facile assembly of a graphitic carbon nitride film at an air/water interface for photoelectrochemical NADH regeneration

“…6a). 52,53 In this case, the CNS or CNS-Gr film harvests incident visible light, and the resulting photogenerated electrons reduce M to M 1 . Then, M 1 accepts a proton from water to generate M 2 .…”

“…S11 †). 53,57 Integration of an excess amount of graphene was found to be detrimental to the photoelectron generation. Under the optimal bias of −0.9 V (vs. Ag/AgCl), the catalytic performance for photoelectrochemical NADH regeneration was studied under visible light, in the presence of M as the mediator and water as the electron donor.…”

Photoelectrochemical CO2 Reduction to Formate with the Sacrificial Reagent Free System of Semiconductor Photocatalysts and Formate Dehydrogenase

“…As the NAD 2 is an inactive co‐enzyme for FDH from Candida boidini , therefore, it is quite difficult to achieve the light‐driven the CO 2 reduction to formate with the system based on the NAD + /NADH photoredox by visible‐light sensitizer and FDH. In contrast, some studies on the light‐driven CO 2 reduction to formate with FDH using the NAD + photoreduction by a catalyst via the electron carrier such as rhodium complex or biocatalyst, ferredoxin‐NADP + reductase (FNR) have been reported as shown in Figure …”