. 2019 May 15;10(5):326. doi: 10.3390/mi10050326

Table 3.

Summary of various 2-D nanostructured photocatalysts with reaction conditions, value-added chemicals produced as a result of photocatalytic CO₂ conversion, and key parameters for improved performance.

2-D Nanostructure	Light Source and Reactants	Production Rate of Value-Added Chemicals	Key Parameters for Improved Performance	Ref.
g-C₃N₄/N-TiO₂ nanosheets	300 W Xenon arc lamp CO₂ bubbled through Deionized water	After 12 h of irradiation CO: 14.73 µmole/g, employing CT7 sample CO: 5.71 µmole/g CH₄: 3.94 µmole/g, employing sample CT5	Moderate surface area Extended light absorption Efficient charge separation at the heterojunction Product selectivity due to band regulation	[62]
TiO₂ nanosheets modified with sulfuric acid	500 W Xe Arc lamp CO₂ and water vapors	After 4 h of irradiation CH₄: 7.63 µmole/g	Acidification facilitates oxidation of water by Ti-OH Ti³⁺ active sites i.e., oxygen vacancies enhanced adsorption of CO₂ Efficient charge separation	[67]
Ultrathin TiO₂ nanosheets	300 W Hg Lamp CO₂ bubbled through Solution of photocatalyst powder in water	Formate formation 1.9 µmole/g h 450 times higher than counterpart 9 time higher than commercially available anatase TiO₂	Surface area increased Promoted life time of electron Efficient charge separation across the 2-D path	[65]
Cu₂O nanoparticles loaded on TiO₂ pillared K₂Ti₄O₇ layers	Polychromatic light AM 1.5 from solar simulator CO₂ and water vapors	After 5 h of irradiation CH₃OH: 2.93 µmole/g 2 times more as compared to pristine sample	Increased surface area Visible light absorption Efficient charge separation	[68]
Cu modified g-C₃N₄ sheets with TiO₂ nanoparticles	254 nm UV Lamp as a UV light source 500 W Xe arc lamp as a visible light source CO₂ bubbled through the water solution containing photocatalyst sample	After 8 h of irradiation under UV light CH₃OH: 2574 µmol/g, HCOOH: 5069 µmol/g Under Visible light CH₃OH: 614 µmol/g, HCOOH:6709 µmol/g Optimum sample: 3 wt.% Cu and 30:70 ratio of g-C₃N₄ and TiO₂	Extended light absorption and efficient charge separation by copper doping Band edges alignment reflects the selectivity for CH₃OH and HCOOH	[71]
TiO₂ nanoparticles on Ti₃C₂ nanosheets	UV LED 3 W 365 nm CO₂ and water vapor generated in situ by reaction of NaHCO₃ and HCl	CH₄: 0.22 µmole/ h for 50 mg sample with small amounts of CH₃OH and C₂H₅OH	Improved surface area Nanosheets providing active sites Efficient electron hole separation	[69]
Pt nanoparticles loaded ultrathin TiO₂ nanosheets	300 W Xenon lamp CO₂ and Water vapors	CH₄: 66.4 µmole/h g CO: 54.2 µmole/h	26 times higher surface area Efficient electron hole separation Improved CO₂ adsorption due to defective surface	[66]
2-D g-C₃N₄ with 0-D TiO_2−x nanoparticles	300 W Xenon lamp CO₂ bubbled through solution containing 5 mg photocatalyst dispersed in 5 mL of solution of MeCN/TEOA with cocatalyst of Co(bpy)₃²⁺	After 5 h of irradiation CO: 388.9 μmol/g 5 times higher than pristine g-C₃N₄	Promoted charge transfer due to electron channel formed between g-C₃N₄ and TiO₂	[64]