Engineering the Surface of a Polymeric Photocatalyst for Stable Solar‐to‐Chemical Fuel Conversion from Seawater. Issue 14 (26th June 2019)

• Record Type: Journal Article
• Authors: Mishra, Biswajit; Mishra, Sabyasachi; Satpati, Biswarup; Chaudhary, Yatendra S.
• Is Part Of: ChemSusChem. Volume 12:Issue 14(2019)
• Page Start: 3383
• Page End: 3389
• Publication Date: 2019-06-26
• Subjects: charge-carrier dynamics -- CO2 photoreduction -- polymeric photocatalyst -- seawater -- solar H2 generation; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201900388
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: The design of an efficient and highly selective organic polymeric semiconductor photocatalyst consisting of Earth‐abundant elements for solar fuel generation using seawater, and also deionized water, as a proton source is reported. The mesoporous g‐C3 N4 synthesized using a conventional precursor (urea) shows significant H2 generation (ca. 33 000 μmol h −1 g −1 ) and drives the photoreduction of CO2 to CH4, along with trace amount of methanol. However, when the chosen precursor cyanamide is used, drastic improvement in H2 generation (ca. 41 600 μmol h −1 g −1 ) and CO2 photoreduction is observed. The introduction of a surface nitrogen deficiency and modification of the surface with Cu 0 further enhances solar H2 generation (ca. 50 000 μmol h −1 g −1 ) and CO2 photoreduction (3.12 μmol h −1 g −1 ) activity, respectively, owing to improvement in light harvesting and charge separation, as revealed by a shorter average lifetime of 3.52 ns and higher Stern–Volmer quenching constant value of approximately 11.2 m −1 . In addition, improved selectivity in CO2 photoreduction to only CH4 is also observed. The designed photocatalytic system is stable, with the solar H2 generation rate increasing even after 20 h under continuous illumination with a turnover number of 6500. When seawater used instead of deionized water, the overall solar fuel generation efficiencies of all photocatalysts marginally decreased owing to a decrease in the photogenerated charge‐carrier separation efficacy. Abstract : Active selection : Rational choice of the precursor and surface engineering can lead to drastic enhancement in the solar H2 generation activity (ca. 50 000 μmol h −1 g −1 ) and CO2 ‐to‐CH4 conversion selectivity, owing to the enhanced light harvesting, exciton separation, and faster charge‐transfer kinetics. The designed photocatalytic system is stable with the solar H2 generation rate increasing under continuous illumination for up to 20 h and a turnover number of 6500.