Qihua Yang

Precise photocatalytic modulation of the NAD+/NADH redox balance is critical for advancing both biocatalytic cascade reactions and photodynamic therapy, yet this goal remains elusive due to the scarcity of efficient, broad-spectrum photocatalysts with orthogonal redox regulation capabilities. Herein, we report a bifunctional covalent organic framework-polyoxometalate (COF-POM) composite that enables bidirectional photocatalytic interconversion between NAD+ and NADH under red visible light irradiation, achieving 77.0% yield for NADH regeneration and nearly quantitative conversion in NADH oxidation. Strikingly, cyt c-mediated anaerobic NADH oxidation was successfully realized, enabling spatiotemporally precise modulation of the intracellular NAD+/NADH redox balance. Mechanistic investigations reveal that POM integration synergistically reinforces the built-in electric field of the COF matrix, substantially accelerating photogenerated charge separation and interfacial transfer kinetics. This work establishes a generalizable strategy for constructing high-performance photocatalysts to enable precise NAD+/NADH redox balance regulation for future tumor metabolic intervention.

Covalent organic frameworks are promising photocatalysts for H₂ generation; however, their efficiency is limited by energy dissipation arising from hot electron loss and carrier recombination. In this work, we introduce interlayer dislocation and polarization in covalent organic frameworks to extend hot electron lifetime to 37.1 ± 2.0 ps, activating a photocatalytic H₂ generation rate of 429.4 ± 3.7 mmol g⁻¹ h⁻¹ and apparent quantum yield of 85 ± 1% at 420 nm. Ultrafast spectroscopy and theoretical calculation elucidate the underlying mechanisms of hot electron production: interlayer dislocations induce energy-band anti-crossing at the K point in the Brillouin zone, suppressing acoustic-phonon scattering to contribute 8.4 times extension of both hot and cooled electrons; polarization effects reduce exciton dissociation and carrier recombination, further increasing carrier and optical-phonon concentration to achieve hot-phonon bottleneck and 180 times of hot electron duration. This study validates hot-electron-enhanced photocatalytic hydrogen generation and offers a general strategy for manipulating hot electrons in two-dimensional photocatalysts.

Solar-driven in situ nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] regeneration provides a sustainable route for producing high-value chemicals using NAD(P)H-dependent reductases. However, its efficiency is frequently restricted by the low charge separation efficiency of photocatalysts. To address this limitation, we developed a series of built-in electric field multivariate covalent organic framework (MTV-COF) photocatalysts with donor–acceptor–acceptor (D–A–A) structures to enhance the charge separation. The resultant MTV-COFs with a 0.06 wt % immobilized Rh cocatalyst achieved a NADH regeneration rate of 763.5 mol·mol_Rh^–1·h^–1 with 95.7% regioselectivity, surpassing the performance of most reported photocatalysts. This is ascribed to the significantly enhanced separation and transfer efficiency of photogenerated electrons and minimized steric hindrance within the COF pores. Furthermore, coupling this highly efficient NADH-regenerating photocatalyst with enzymatic reduction reactions enabled continuous l-glutamic acid and (S)-2-phenylpropanol production, reaching total NADH regeneration turnover numbers of 80 and 71, respectively, which are significantly higher than previously reported values. This work underscores the critical importance of the D–A–A structural motif design in MTV-COF-Rh to generate a built-in electric field to enhance the charge separation for efficient photocatalysis.