CO2 is not only the primary cause of climate change but also an abundant and recyclable carbon resource. The breakthrough in emerging disruptive technologies such as carbon capture and storage (CCS), power-to-X, and direct air capture (DAC) is fundamental to achieving carbon neutrality. Among these technologies, artificial photosynthesis offers an attractive method for recycling carbon dioxide and water into fuels and chemicals using solar energy (CO2 + H2O + sunlight → fuels + chemicals). It holds great promise for addressing the critical challenges associated with elevated CO2 concentrations and securing a sustainable supply of fuels and chemicals for economic sectors.
Solar energy is a substantial source of various renewable energies such as wind, photovoltaic, and biomass. It is widely considered as the dominant energy source in the post-fossil fuel era due to its infinite, low-cost, and renewable properties. However, the fluctuating, intermittent, and low-density properties of solar energy pose tremendous challenges for future economic sectors, particularly for heavy-duty and/or long-distance energy and power sectors such as aviation and maritime industries. From an energy conversion perspective, artificial photosynthesis enables the storage of low-energy-density and intermittent solar energy into storable and energy-dense chemical fuels at a large scale. Maximally utilizing the full solar spectrum is critical to breaking the efficiency bottleneck of solar-to-chemical transformation, which remains greatly challenging and is associated with the trade-off between light absorption and charge potential. From a microscopic point of view, artificial photosynthesis is an extremely complex process involving photon harvesting, charge separation, and chemical reactions. It is highly critical to optimize the synergy of these species/steps to break the energy efficiency bottleneck of solar-to-chemical transformation.
From a molecular perspective, artificial photosynthesis suffers from an intricate reaction network and the concurrent reconstruction of various chemical bonds such as C–C, C=O, C–H, C–O, and H–H. Considering the thermodynamic and kinetic hurdles, it is an extraordinary challenge to directly produce multi-carbon compounds such as diesel, jet fuel, and value-added chemicals from CO2 and H2O. Hence, the integration of artificial photosynthesis with well-developed technologies such as the Fischer–Tropsch process seems to be a plausible means. In a broad sense, artificial photosynthesis can be performed through various configurations such as photocatalysis, photoelectrocatalysis, and photovoltaic + electrocatalysis. Therefore, the advancement of power-to-X technology is also beneficial for artificial photosynthesis.
This special issue aims to demonstrate the basic profile of artificial photosynthesis. More specifically, it consists of different contributions in the form of research articles, views & comments, and mini-reviews, mainly focusing on the research effort of improving solar-to-fuel energy efficiency and revealing the reaction mechanism. The challenges and advances of artificial photosynthesis are also commented upon.
Although many technical and economic challenges need to be addressed, artificial photosynthesis will undoubtedly play a vital role in the shift of economic sectors toward a carbon-neutral future, especially if it works well in synergy with other emerging technologies such as DAC and CCS, as well as mature technologies such as Fischer–Tropsch and proton exchange membrane fuel cell (PEMFC). Joint efforts from the broad community of academia, industry, finance, and governance will facilitate the virtual success in “Toward Carbon Neutrality by Artificial Photosynthesis. ”
PDF
(516KB)
