Improving Photocatalytic Energy Conversion via NAD(P)H

Abstract

The reduced form of nicotinamide adenine dinucleotide (NAD(P)H) behaves as an energy/chemical "currency", carrying hydrogen in a biologically convertible form and donates electrons in numerous biotransformations and artificial photosynthesis. Its high cost necessitates its regeneration for reuse where photocatalysis using light energy is attractive. However, high NAD(P)H yield is only achievable via organic mediators to transfer electrons.Here, we analyse the current issues in catalytic NAD(P)H regeneration and show that a continuous-flow reactor system can realise selective NAD(P)H regeneration with 100% yield using Pt/C3N4 as a photocatalyst.

Single-Atom Photocatalysts for Emerging Reactions

“…Solar energy has exhibited great potential as a promising alternative to substituting the traditional energy sources because it is clean, renewable, abundant, affordable, and everlasting. , Due to the unpredictable nature of weather, it is challenging to make use of solar light under poor weather conditions and/or at night; therefore, it is necessary to transform solar energy into new forms of energy that are storage-stable. Up to date, solar energy has been extensively utilized to produce storable and transportable fuels with high energy capacity as well as value-added chemicals. − Among various solar energy conversion techniques, photocatalysis is deemed as a promising, environmentally benign, and cost-effective strategy to generate both fuels and high-value chemicals. − During the past decades, numerous studies have been focused on several well-known reactions (e.g., H 2 production, − N 2 fixation − and CO 2 conversion − ) achieved via photocatalysis. Recently, a range of emerging photocatalytic reactions generating fuels and/or valuable chemicals has been attracting increasing attention. − These emerging reactions can be categorized into three different types, i.e., reduction reactions, oxidation reactions, and redox reactions, based on their specific photocatalytic reaction mechanisms.…”

Protein‐Mediated Biosynthesis of Semiconductor Nanocrystals for Photocatalytic NAD(P)H Regeneration and Chiral Amine Production

“…These results imply that part of the formed NADPH is enzymatically inactive due to a nonselective photoreduction process that occurs directly by the nano‐bio hybrids [48, 49] . Enzymatically inactive reduced NADP + , e.g., 1,6‐NADPH, 1,2‐NADPH, and (NADP) 2 dimer, share a similar UV/Vis absorption as the enzymatically active 1,4‐NADPH isomer [45] . To enable the formation of enzymatically active 1,4‐NADPH, we coupled the ferredoxin NADP + reductase (FNR) enzyme to the nano‐bio hybrid photocatalytic mixture.…”

“…Furthermore, NADPH is a crucial cofactor for a wide array of reductive enzymes (i.e., oxidoreductases) that are used extensively in the chemical and pharmaceutical industries. [45] Therefore, we have tested the compatibility of the designed SP1@CdS QDs configuration to facilitate the photocatalytic reduction of NADP + to NADPH. The latter absorbs light at 340 nm; therefore, we followed its generation using UV/Vis spectroscopy.…”

“…[48,49] Enzymatically inactive reduced NADP + , e.g., 1,6-NADPH, 1,2-NADPH, and (NADP) 2 dimer, share a similar UV/Vis absorption as the enzymatically active 1,4-NADPH isomer. [45] To enable the formation of enzymatically active 1,4-NADPH, we coupled the ferredoxin NADP + reductase (FNR) enzyme to the nanobio hybrid photocatalytic mixture. Naturally, the FNR is expressed in photosynthetic organisms and accepts the photo-excited electrons from photosystem I (mediated by the ferredoxin protein) to enable the generation of NADPH that subsequently drives the Calvin cycle.…”

“…In nature, NADPH plays a key role in anabolic pathways, e.g., photosynthesis and CO 2 fixation. Furthermore, NADPH is a crucial cofactor for a wide array of reductive enzymes (i.e., oxidoreductases) that are used extensively in the chemical and pharmaceutical industries [45] . Therefore, we have tested the compatibility of the designed SP1@CdS QDs configuration to facilitate the photocatalytic reduction of NADP + to NADPH.…”