Artificial Photosynthesis: Learning from Nature

Abstract

Artificial photosynthesis has been devised and investigated in pursuit of solving the 21st century's energy problem. Despite significant advances in recent decades, applying the technology in real life is still a challenging subject for scientists. As the term “artificial photosynthesis” stems from mimicking natural photosynthesis, we can learn from nature's strategies which have evolved over 3.4 billion years. This Review highlights important strategies of natural photosynthesis which can be borrowed for highly efficient and robust artificial photosystems for solar fuel production. Starting with a brief description of photosystem II in natural photosynthetic autotrophs, three relevant bioinspired strategies are discussed in this article: i) accumulative charge transfer, ii) photoprotection, and iii) self‐healing. Next, development of artificial photosystems mimicking those strategies will be discussed. Finally, remaining challenges and perspectives for future development of artificial photosynthesis are described.

Cobalt Carbonate as an Electrocatalyst for Water Oxidation

“…Water oxidation (2 H 2 O!O 2 + 4H + + 4e À )i sakey step in artificial photosynthesis. It also has significance in biological processes, [1][2][3][4][5] solar energy conversion, [6][7][8][9][10] and water electrolysis. [11][12][13][14] But the process is sluggish because it requires the loss of both 4e À /4 H + and concomitant formation of the OÀO bond.…”

Light‐driven catalysis with engineered enzymes and biomimetic systems

“…An inspiration for the continuing growth of photocatalysis research is at the convergence of photochemistry and biocatalysis: photosynthesis. It has long been desired that the sun, a renewable resource, would replace the nonrenewable feedstocks that drive human life and industry [20,25,26,[33][34][35].…”

“…Although there are many ways in which light may provide the energy to drive a reaction, the process as inspired by photosynthesis contains several fundamental steps: light absorption (1), charge separation (2), charge accumulation (3), catalysis (4), and replenishment of electrons (5) (numbers indicate steps as illustrated in Fig. 1) [20,21,34,[36][37][38]. Re-r Some light-driven biocatalytic reactions store light energy in the form of a fuel.…”

“…Formation and efficient separation of an electron-hole pair are carried out using complex molecular architectures in natural photosynthesis [39]. A variety of strategies have been implemented in artificial systems, such as directly tethering molecules, to mitigate energy loss and charge recombination [34,40]. As light is absorbed, charge is accumulated to fuel catalysis (3).…”

“…For proton reduction to become a viable route to producing hydrogen as a solar fuel for widespread use, an integral part of the overall process is water oxidation, which allows water to serve as a source of the needed protons and electrons, similar to natural photosynthesis [34,35,84,184]. Transforming this abundant feedstock as plants do is challenging, and en route to the selective four-electron, four-proton oxidation to O 2 are reactive partially reduced oxygen species [25,34,38]. The development of catalysts of the water oxidation reaction has utilized inorganic bulk or nanocrystalline materials for heterogeneous catalysis [185,35] and inorganic molecular systems for homogeneous catalysis [21,36].…”