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Engineering the Surface of a Polymeric Photocatalyst for Stable Solar‐to‐Chemical Fuel Conversion from Seawater
Author(s) -
Mishra Biswajit,
Mishra Sabyasachi,
Satpati Biswarup,
Chaudhary Yatendra S.
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201900388
Subject(s) - solar fuel , photocatalysis , seawater , methanol , quenching (fluorescence) , chemistry , materials science , photochemistry , chemical engineering , catalysis , organic chemistry , oceanography , physics , quantum mechanics , engineering , fluorescence , geology
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‐C 3 N 4 synthesized using a conventional precursor (urea) shows significant H 2 generation (ca. 33 000 μmol h −1 g −1 ) and drives the photoreduction of CO 2 to CH 4 , along with trace amount of methanol. However, when the chosen precursor cyanamide is used, drastic improvement in H 2 generation (ca. 41 600 μmol h −1 g −1 ) and CO 2 photoreduction is observed. The introduction of a surface nitrogen deficiency and modification of the surface with Cu 0 further enhances solar H 2 generation (ca. 50 000 μmol h −1 g −1 ) and CO 2 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 CO 2 photoreduction to only CH 4 is also observed. The designed photocatalytic system is stable, with the solar H 2 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.