A review of recent progress in gas phase CO2 reduction and suggestions on future advancement

Abstract The 2018 report by the Intergovernmental Panel on Climate Change (IPCC) details how rapidly Earth's climate is changing due to rising atmospheric CO2 concentrations. Maintaining a recognizable terrestrial ecosphere over the next eighty years will require, by 2030, a decrease in global CO2 emissions by 45% from their 2010 levels, with zero net global emissions by 2050. However in 2018, global CO2 emissions were 112% of 2010 levels. Our interest lies in the use of sunlight to efficiently recycle CO2 from a waste combustion product, together with water vapor, into hydrocarbon fuels that can be readily stored, transported and used within the current energy infrastructure. While the concept is intriguing until 2019 such a solar fuels technology has been limited by the vanishingly small CO2-to-fuel photoconversion efficiencies achieved. Recently there has been a significant advance in CO2 to fuel photoconversion efficiencies with researchers achieving, in an unoptimized system, over a 6 h period, a Joule (sunlight) to Joule (fuel) photoconversion efficiency of 1%. Just as photovoltaics went from niche market devices of low photoconversion efficiency to highly efficient devices enabling a global industry, such a sunlight-to-fuel photoconversion efficiency suggest utility-scale implementation of a sunlight-powered recycled-CO2 to hydrocarbon fuel technology is realistically achievable in the near future. With an aim towards enabling significant advances in the field, leading to translation of the technology from laboratory to industrial-scale application, we examine what we believe are the key opportunities for achieving significant advances in sunlight-to-fuel photoconversion efficiencies.