Tale of Two Layered Semiconductor Catalysts toward Artificial Photosynthesis

Abstract

The ever-increasing reliance on nonrenewable fossil fuels due to massive urbanization and industrialization created problems such as depletion of the primary feedstock and raised the atmospheric CO2 levels causing global warming. A smart and promising approach is artificial photosynthesis that photocatalytically valorizes CO2 into high-value chemicals. The inexpensive layered semiconductors like g-C3N4 and rGO or GO have the potential to make the process practically feasible for real applications. The suitable band positions with respect to the reduction potentials coupled with the typical surface properties of these layered semiconductors play a beneficial role in photoreduction of CO2. Additionally, the creation of heterojunction interfaces to achieve the Z-scheme by anchoring g-C3N4 and rGO with another semiconductor with proper band alignment and dispersing plasmonic nano metals to obtain Schottky barriers on the layered surfaces also help retarding the electron–hole recombination and boost up the catalytic efficacy. Extensive exploration happened in recent years toward artificial photosynthesis over these materials, which needs a critical compendium. Surprisingly, in spite of the recent explosion of studies on photocatalytic reduction of CO2 over metal-free semiconductors, there is not a single review on comparing the mechanistic aspects of photoreduction of CO2 over the layered semiconductors g-C3N4 and rGO. This review stands out as a unique documentation, where the mechanism of photocatalytic reduction of CO2 over this set of materials is critically examined in the context of band and surface modifications. An overall conclusion and outlook at the end indicates the need to develop prototypes for artificial photosynthesis with these well-studied semiconducting layered materials to yield solar fuels.

From Trash to Treasure: Probing Cycloaddition and Photocatalytic Reduction of CO2 over Cerium-Based Metal–Organic Frameworks

“…The catalyst must be porous with a high surface basicity as selective storage and encapsulation of acidic CO 2 is the primary step before cycloaddition reactions. For efficient photoreduction of CO 2 , the conduction band (CB) minima of the semiconductor photocatalyst should be positioned energetically higher (more negative) compared to the corresponding CO 2 reduction potential, and the valance band (VB) maxima should be well below (more positive than) the water oxidation level to produce sufficient protons. , Utilizing the universal solvent water instead of any other organic hole scavengers like triethanolamine is a greener way to carry out the artificial photosynthesis. Therefore, water stability is another important requirement for a suitable catalytic material.…”

2D Molybdenum Sulfide‐Based Materials for Photo‐Excited Antibacterial Application

“…[204,205] The Schottky barrier will capture the photogenerated e − , thereby promoting the separation of photogenerated electron-hole pairs, each of which plays a role in the redox reaction. [204,206,207] Based on the above advantages, depositing precious metals is one of the common means of enhancing the catalytic activity of MoS 2 . For instance, Maimaitizi et al synthesized flower-like Pt/N-MoS 2 for nitrogen fixation via simple photo-ultrasound-assisted method, where the impurity energy levels introduced by N doping expanded the visible light absorption region, and the deposited Pt nanoparticles formed the Schottky barrier that accelerated carriers separation and transportation (Figure 8A).…”

“…[ 204,205 ] The Schottky barrier will capture the photogenerated e − , thereby promoting the separation of photogenerated electron‐hole pairs, each of which plays a role in the redox reaction. [ 204,206,207 ] Based on the above advantages, depositing precious metals is one of the common means of enhancing the catalytic activity of MoS 2 . For instance, Maimaitizi et al.…”

Current density in solar fuel technologies

“…Another promising design, which exploits the possibility for a two-step light absorption somewhat similar to Z-scheme in PP, 61,62 is the tandem PEC configuration. 63,64 In this case, two photoelectrodes are used synergistically to increase both photocurrent and photovoltage, i.e., by maximising the absorbed portion of the solar spectrum and optimising the electronic band gaps/band edges positions.…”