Solar Photochemistry with Transition Metal Compounds Anchored to Semiconductor Surfaces

Abstract

There exists a critical need for sustainable power on a terawatt (TW ¼ 10 12 W) scale. 1,2 As the world's need for energy is related to the number of people on Earth, a staggering 45% population growth over the last quarter-century equates to roughly 2 billion people and a 6 TW ($63%) increase in needed power. 3 In addition, the urbanism of third-world and industrialized nations and cities has led to an increase in the demand for fuel that has driven gas and oil prices to record highs. 3 Regardless of price, the continued use of fossil fuels cannot be a long-term solution as they come from a limited stock and the deleterious environmental consequences of their combustion have become self-evident. 4,5 The increased average global temperature and rates of glacial melting measured over the past few decades are telling signs. [6][7][8][9] Concern should be elicited as ice-core data correlate temperature with greenhouse gas concentrations over the past half-a-million years. The present 380 ppm atmospheric CO 2 levels exceed any values attained over the same time period. 5,6 Further, other than natural photosynthesis, there exist no obvious means by which we can decrease today's level. Thus, population, energy demand, and fuel prices do not convey the severity of the need for sustainable energy.It is our belief that molecular assemblies, particularly molecules arranged at semiconductor interfaces, will one day efficiently harvest and convert energy from the Sun, thereby providing sustainable, carbon-neutral power for future generations. The Sun is in fact the only source that on its own can provide the TWs of power needed. It has been shown that the amount of solar energy reaching the Earth in one day could power the planet for an entire year. 7,8 Remaining is the important challenge of harvesting, converting, and storing this energy in a cost-effective way. Coordination Physical Inorganic Chemistry: Reactions, Processes, and Applications Edited by Andreja Bakac