that HCOOH is the more preferred product than CH 3 OH. For Pt/C 3 N 4 , the strong
interaction between Pt and HCOOH* (1.06 eV) and the favorable CH 2 * and H 2 O*
generation instead of CH 2 OH* hydrogenation made it the suitable candidate for CH 4
production.
12.5 Summary and Perspective
So far, the synthesis of photocatalyst with cocatalysts incorporation and the unique
properties of various cocatalysts in CO2PR have been carefully summarized. The
roles of these cocatalysts such as promote the charge separation efficiency, improve
the adsorption of the CO 2 amount, expand the light harvesting range, provide active
sites for the activation of CO 2 or other intermediates, etc. also have been briefly
discussed. Besides, the important roles of spatial configurations of the photocatalyst
composite and the deposition amount of the cocatalysts are also illustrated carefully:
inappropriate incorporation of cocatalysts would lead to negative effect of the
photocatalyst’s performance; on the contrary, rational structure design such as the
Z-scheme model or cocatalysts with spatial separated configurations could enhance
the performance of the photocatalyst. It should be noted that we mainly focus on the
solid-state cocatalysts in this chapter; beside this, the molecular-state cocatalysts like
metal complex and dyes also could act as the cocatalyst in the CO2PR; however, this
type of photocatalytic system is often conducted in the liquid phase and in the
presence of hole scavenger, which is quite different from the solid-phase cocatalysts,
so these types of cocatalysts are not discussed in here.
Although numerous efforts have been done in the selection of suitable cocatalysts
and the development of fine structures of photocatalyst in CO2PR, many problems
still existed and need to be answered and improved:
1. The CO2PR evaluation method is alternative among different research groups;
therefore, the product yields comparison of different photocatalysts which is
problematic; other evaluation methods such quantum yield efficiency and turnover number (TON) are highly encouraged in the following studies.
2. The origination of the products should be verified carefully; the organic impurities or carbon-involved species also could be converted into the products and
cause the illusion result; therefore, control experiment of CO 2 photocatalytic
reduction reaction should be conducted with the use of isotope-labeled
13 CO 2
as the reactant for comparison.
3. The reaction pathways and mechanism in CO2PR are still ambiguous; deep
understanding of the CO2PR could bring inspiration to the researchers to design
highly efficient and selective catalysts; in this case, the DFT calculation along
with the in situ characterizations is highly advocated.
4. The stability of the cocatalysts in the long-term CO2PR reaction is another
concern; many photocatalysts suffer from low stability due to the carboninvolved species accumulation and deactivate gradually; therefore, the
12.5 Summary and Perspective
301
interaction between Pt and HCOOH* (1.06 eV) and the favorable CH 2 * and H 2 O*
generation instead of CH 2 OH* hydrogenation made it the suitable candidate for CH 4
production.
12.5 Summary and Perspective
So far, the synthesis of photocatalyst with cocatalysts incorporation and the unique
properties of various cocatalysts in CO2PR have been carefully summarized. The
roles of these cocatalysts such as promote the charge separation efficiency, improve
the adsorption of the CO 2 amount, expand the light harvesting range, provide active
sites for the activation of CO 2 or other intermediates, etc. also have been briefly
discussed. Besides, the important roles of spatial configurations of the photocatalyst
composite and the deposition amount of the cocatalysts are also illustrated carefully:
inappropriate incorporation of cocatalysts would lead to negative effect of the
photocatalyst’s performance; on the contrary, rational structure design such as the
Z-scheme model or cocatalysts with spatial separated configurations could enhance
the performance of the photocatalyst. It should be noted that we mainly focus on the
solid-state cocatalysts in this chapter; beside this, the molecular-state cocatalysts like
metal complex and dyes also could act as the cocatalyst in the CO2PR; however, this
type of photocatalytic system is often conducted in the liquid phase and in the
presence of hole scavenger, which is quite different from the solid-phase cocatalysts,
so these types of cocatalysts are not discussed in here.
Although numerous efforts have been done in the selection of suitable cocatalysts
and the development of fine structures of photocatalyst in CO2PR, many problems
still existed and need to be answered and improved:
1. The CO2PR evaluation method is alternative among different research groups;
therefore, the product yields comparison of different photocatalysts which is
problematic; other evaluation methods such quantum yield efficiency and turnover number (TON) are highly encouraged in the following studies.
2. The origination of the products should be verified carefully; the organic impurities or carbon-involved species also could be converted into the products and
cause the illusion result; therefore, control experiment of CO 2 photocatalytic
reduction reaction should be conducted with the use of isotope-labeled
13 CO 2
as the reactant for comparison.
3. The reaction pathways and mechanism in CO2PR are still ambiguous; deep
understanding of the CO2PR could bring inspiration to the researchers to design
highly efficient and selective catalysts; in this case, the DFT calculation along
with the in situ characterizations is highly advocated.
4. The stability of the cocatalysts in the long-term CO2PR reaction is another
concern; many photocatalysts suffer from low stability due to the carboninvolved species accumulation and deactivate gradually; therefore, the
12.5 Summary and Perspective
301