Biomimetic photocatalyst Ce/TCPP-UiO-66-NH2 for NADH regeneration and CO2 activation

CO2 activation and conversion by enzymes to produce value-added multi-carbon compounds under mild conditions show significant impact on carbon neutrality. However, the enzyme co-factor NADH is expensive and the regeneration is still challenging for the enzyme reaction process. Inspired by natural photosynthesis, this study successfully developed a biomimetic photocatalyst Ce/TCPP-UiO-66-NH2 (TCPP: mesotetrakis (4-carbox-yphenyl) porphine) for NADH regeneration and CO2 activation. Structure analysis and spectra showed that the co-doping of Ce and TCPP reduced the band gap width of UiO-66-NH2, improved the separation efficiency of photo-generated carriers, and endowed it with excellent photocatalytic performance. The synthesized bio-mimetic photocatalyst Ce/TCPP-UiO-66-NH2 was then applied for NADH regeneration. The regeneration efficiency of NADH can reach up to 95 % after 3 h of light reaction, which was about 1.6 times higher than that of the control group. Ultra-fast femtosecond time-resolved transient absorption (fs-TA) showed that Ce/TCPP-UiO-66-NH2 possessed the shortest average decay time (tau = 1.12 ps), indicating shorter average life-time of carriers after Ce doping, thus suppressing hole-electron recombination. Finally, the key enzyme formate dehydrogenase (FDHPa) for CO2 activation was immobilized on the membrane, combining with light regeneration of NADH for CO2 production to formate. The formate yield (3.1 mM) was 16 times higher than that of the control group (0.19 mM). This work provided an effective strategy and efficient photocatalyst for the biomimetic photocatalytic activation of CO2 to formate, which is an indispensable bridge for the further high-valuable Cn compounds production by biocatalysis.