Current Challenges of CO2 Photocatalytic Reduction Over Semiconductors Using Sunlight

Abstract

The possibility of producing fuels and chemicals from CO 2 using semiconductors and sunlight holds the promise of storing abundant, despite diluted, solar power in the form of energy-rich chemicals. In principle, this process can operate under very soft conditions, and this may facilitate a distributed production of solar fuels. However, photocatalytic reduction of CO 2 over semiconductors has proved to be a very challenging process, and the yields currently attained are rather limited. Accordingly, a number of drawbacks should be overcome if this process is expected to become a feasible alternative for generation of sustainable fuels and chemicals in the midterm. First, the conversion rate of CO 2 should be boosted to reach values in the order of millimoles per hour and gram of semiconductor. In addition, several relevant engineering challenges should be conveniently solved before this technology becomes viable. In this chapter, we evaluate thoroughly the most recent advances on the understanding of this photocatalytic process, and at the same time, we try to define the most relevant aspects that scientific research should address in the near future.

Silver–Gold Bimetal-Loaded TiO2 Photocatalysts for CO2 Reduction

“…Nevertheless, significant progress has been made in the last years and the path forward is promising . Artificial photosynthesis (AP) encompasses, among other reactions, the transformation of CO 2 to useful molecules for chemistry and energy . The so-obtained solar fuels would provide not only a direct way of storing solar energy into chemical vectors, but also the reutilization of CO 2 emissions to complement carbon capture and storage (CCS) technologies .…”

Fundamental Insights into Photoelectrocatalytic Hydrogen Production with a Hole-Transport Bismuth Metal–Organic Framework

“…In the search for carbon-neutral technologies able to provide sustainable energy, it is crucial to develop processes that effectively exploit renewable natural resources. In this context, scientists are allocating efforts to convert and store solar energy into chemicals and fuels, mimicking photosynthesis. − Currently, the development of artificial photosynthesis depends on the search for new, efficient photocatalytic materials able to be used as photoelectrodes in photoelectrochemical cells (PECs) to produce solar fuels, such as hydrogen through water splitting or CO 2 photoreduction products . Generally speaking, a photoelectrocatalyst is a material that can be activated upon light absorption, leading to charge generation and separation of electron–hole (e – -h + ) pairs that trigger both reduction and oxidation reactions.…”

Grand Challenges for Catalytic Remediation in Environmental and Energy Applications Toward a Cleaner and Sustainable Future

“…Besides the conventional heterogeneously catalyzed thermal CO 2 hydrogenation, remarkable research efforts have been devoted for the photocatalytic and/or electrocatalytic reduction of CO 2 into hydrocarbons or oxygenates as well (Kondratenko et al, 2013;de la Peña O'Shea et al, 2015;Qiao et al, 2016;Francke et al, 2018;Zhang et al, 2018;Ali et al, 2019;Albero et al, 2020;Zhu et al, 2020). This constitutes a promising approach toward the production of a variety of valueadded products or fuels, such as methane, ethylene, methanol, formaldehyde, formic acid, carbon monoxide, using intermittent renewable energy sources (Francke et al, 2018;Wang et al, 2018;Zhang et al, 2018).…”