Recent progress in homogeneous multielectron transfer photocatalysis and artificial photosynthetic solar energy conversion

As a consequence of global population growth, our modern civilization is facing many upcoming challenges such as gradually depleting energy resources, anthropogenic climate change and other serious environmental issues. In this context, the development of artificial photosynthetic systems for solar energy harvesting and sustainable fuel production represents one of the most attractive long-term strategies to address these important topics. Despite the indisputable benefits, which such a man-made counterpart of the biological solar energy conversion and storage machinery could provide, progress in mimicking the essential functions of natural photosynthesis still remains quite difficult to achieve. While ongoing efforts in replacing the light-harvesting and charge separation function of natural photosystems have led to some remarkable success, many aspects of powering the endergonic chemical reactions required have to be much further elaborated. The current limitations of most artificial photosynthetic systems are related to an inefficient coupling of the catalytic steps necessary for chemical bond formation and for an accumulation of energy rich product molecules (solar fuels). In the present review, some recent breakthroughs in these directions are briefly discussed.