Photocatalytic Synthesis of High-Energy-Density Fuel: Catalysts, Mechanisms, and Challenges

High-energy-density liquid hydrocarbon fuels are generally synthesized using various chemical reactions to improve the performance (e.g., range, load, speed) of aerospace vehicles. Compared with conventional fuels, such as aviation kerosene and rocket kerosene, these liquid hydrocarbon fuels possess the advantages of high-energy-density and high volumetric calorific value; therefore, the fuels have important application value. The photocatalytic process has shown great potential for the synthesis of a diverse range of fuels on account of its unique properties, which include good efficiency, clean atomic economy, and low energy consumption. These characteristics have led to the emergence of the photocatalytic process as a promising complement and alternative to traditional thermocatalytic reactions for fuel synthesis. Extensive effort has been made toward the construction of catalysts for the multiple photocatalytic syntheses of high-energy-density fuels. In this review, we aim to summarize the research progress on the photocatalytic synthesis of high-energy-density fuel by using homogeneous and heterogeneous catalytic reactions. Specifically, the synthesis routes, catalysts, mechanistic features, and future challenges for the photocatalytic synthesis of high-energy-density fuel are described in detail. The highlights of this review not only promote the development of the photocatalytic synthesis of high-energy-density fuel but also expand the applications of photocatalysis to other fields. Graphic abstract

Advances in Clean Fuel Ethanol Production from Electro-, Photo- and Photoelectro-Catalytic CO2 Reduction

Using renewable energy to convert CO2 to a clean fuel ethanol can not only reduce carbon emission through the utilization of CO2 as feedstock, but also store renewable energy as the widely used chemical and high-energy-density fuel, being considered as a perfect strategy to address current environment and energy issues. Developing efficient electrocatalysts, photocatalysts, and photoelectrocatalysts for CO2 reduction is the most crucial keystone for achieving this goal. Considerable progresses in CO2-based ethanol production have been made over the past decades. This review provides the general principles and summarizes the latest advancements in electrocatalytic, photocatalytic and photoelectrocatalytic CO2 conversion to ethanol. Furthermore, the main challenges and proposed future prospects are illustrated for further developments in clean fuel ethanol production.