Chemoselective NADH Regeneration: the Synergy Effect of TiO_x and Pt in NAD⁺ Hydrogenation

Abstract

The regeneration of the reduced form cofactor nicotinamide adenine dinucleotide (NADH) by NAD + hydrogenation is an economical way for the practical application of biocatalysis but still remains a big challenge due to the low selectivity. Herein, we report that the selectivity to NADH could be greatly promoted by the strong metal−support interaction effect between Pt and TiO 2 . It was found that NADH selectivity determined by enzyme analysis increased with Pt/TiO 2 reduction temperature increasing and reached a maximum of 63.4% at a reduction temperature of 450 °C. The catalysis and characterization results revealed that Pt is the active site for H 2 activation and dissociation and TiO x is responsible for the preferential adsorption of NAD + through amide CO. The selective NAD + hydrogenation to NADH is assisted by hydrogen spillover. The prevention of the direct adsorption of NAD + on Pt sites is necessary to obtain high NADH selectivity, which provides a new designable idea for selective NAD + hydrogenation.

Directing the H2-driven selective regeneration of NADH via Sn-doped Pt/SiO2

“…It was found that the catalyst doped with the lowest amount of Sn (Pt90) gave rise to the highest selectivity to 1,4-NADH, achieving 90%. This is a significant improvement on the previously reported heterogeneous catalysts (which attained a maximum selectivity of 63% 27 ). The improved selectivity can be attributed to directing the adsorption mode of NAD + by disturbing the Pt ensemble.…”

“…17,26 Recently, Yang et al assessed a group of Pt/TiO 2 catalysts in H 2 and achieved a selectivity (and yield) of 63%. 27 To date, supported metal catalysts have failed to deliver any further improvements in selectivity/yield. To overcome this, Vincent et al have borrowed the natural performance of enzymes and used a commercial Pd/C (and carbon) to adsorb NAD + reductase, which then exhibits exclusive selectivity to 1,4-NADH.…”

“…The cause of the reduction in activity is that increasing the extent of Sn doping will cause a dilution of Pt adsorption ensembles. It was suggested by Yang et al that the hydrogenation of NAD + on Pt (supported on TiO 2 ) occurs by the end-on adsorption of the nicotinamide ring via the carbonyl group, 27 and since less surface Pt is available to accommodate CO adsorption, this is likely to contribute to the reduction in activity.…”

“…The maximum yields of 1,4-NADH of 88% and 76% for the Pt90 and Pt75 catalysts are significantly improved from those previously reported for Pt/TiO 2 (up to 63%). 27 The selectivity of the reaction was then investigated by analysing products with 1 H NMR spectroscopy. Fig.…”

Design and Electrochemical Study of Three-Dimensional Expanded Graphite and Reduced Graphene Oxide Nanocomposites Decorated with Pd Nanoparticles for Hydrogen Storage

“…Despite the myriad unique properties of graphene-based materials specific to hydrogen storage applications, carbonaceous materials can only achieve high gravimetric storage capacities (up to 7.5 wt %) under cryogenic temperatures and high pressures. , Unfortunately, the hydrogen storage capacities of carbon-based materials under ambient conditions are significantly low (up to 1 wt %) due to their weak physical interactivity. To achieve desirable storage capacities of graphene-based materials, the functionalization of graphene nanomaterials and decorating them with metal atoms are potential solutions. , The decoration of carbonaceous materials with metal nanoparticles (NPs) such as Pd, , Pt, and Ni can absorb hydrogen via the so-called hydrogen spillover − and Kubas-type − interaction phenomenon. However, the tendency of metal NPs to aggregate on the surfaces of graphene sheets prevents significant hydrogen storage.…”