Natural Versus Artificial Photosynthesis: Pushing Beyond Nature's Limits to Deliver Low-Cost Solar Fuels

Natural photosynthesis (NP) sustains life by coordinating light harvesting, charge separation, multielectron catalysis, carbon fixation, regulation, and repair. Artificial photosynthesis instead aims to convert solar energy selectively into fuels and chemicals through designed light absorbers, interfaces, and catalytic sites. This review compares the two systems across light harvesting, charge separation and transfer, catalytic conversion, photoprotection, and system integration, emphasizing that meaningful comparisons require similar functions, comparable metrics, and clearly defined system boundaries. Field-scale NP typically operates at sub-percent solar-to-biomass efficiencies, whereas selected artificial photosynthetic devices have achieved double-digit solar-to-fuel efficiencies under defined conditions. These values should not be directly ranked because the products and system functions differ. We identify the respective strengths of artificial systems in spectral, interfacial, catalytic, and product control, and of natural systems in regulation, repair, regeneration, and multiscale coordination, providing design principles for efficient, durable, and scalable solar-to-chemical conversion.