Chloroplast-Inspired Artificial Photosynthetic Capsules for Efficient and Sustainable Enzymatic Hydrogenation

Inspired by the structure and function of chloroplast, an artificial photosynthetic alginate (ALG) capsule bearing carboxymethylcellulose (CMC) matric, red phosphorus quantum dots@g-C3N4 (P/CN) tubular photocatalysts, and alcohol dehydrogenase (ADH) is prepared for efficient and sustainable synthesis of methanol from formaldehyde. CMC liquid core resembles grana in the chloroplast to afford a favorable microenvironment for stabilizing ADH, whereas P/CN photocatalysts mimic thylakoid in chloroplast to supply nicotinamide adenine dinucleotide (NADH, the hydride donor) for triggering enzymatic hydrogenation. Moreover, P/CN photocatalysts reinforce the mechanical stability and thereby inhibit the swelling of ALG capsules, thus suppressing the leaching of P/CN photocatalysts and enzymes. The kinetic processes of photocatalytic regeneration and enzyme hydrogenation are investigated, respectively. The optimal coupling of photoenzyme reactions enabled by the capsules achieves the efficient and sustainable production of methanol. Our study offers some guidance for rational construction of integrated and recyclable artificial photosynthetic systems toward a broad range of chemical/biochemical reactions.