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Oxygen‐Functionalized and Ni + x ( x= 2, 3)‐Coordinated Graphitic Carbon Nitride Nanosheets with Long‐Life Deep‐Trap States and their Direct Solar‐Light‐Driven Hydrogen Evolution Activity
Author(s) -
Lakhera Sandeep Kumar,
Pangal Rugma Thekke,
Hafeez Hafeez Yusuf,
Neppolian Bernaurdshaw
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.201901224
Subject(s) - photocatalysis , materials science , graphitic carbon nitride , photoluminescence , x ray photoelectron spectroscopy , photocurrent , water splitting , nitride , hydrogen , charge carrier , oxygen evolution , analytical chemistry (journal) , chemical engineering , nanotechnology , chemistry , catalysis , optoelectronics , biochemistry , organic chemistry , electrode , layer (electronics) , chromatography , engineering , electrochemistry
Graphitic carbon nitride, a 2 D layered photocatalyst coupled with transition metal oxides often shows promising photocatalytic hydrogen evolution activity. However, low surface area and poor charge separation greatly hinder its photocatalytic efficiency. A Ni + x ( x= 2, 3)/O−g‐C 3 N 4 photocatalyst with a very high specific surface area (199 m 2 g −1 ) has been prepared by thermal condensation and wet‐impregnation methods. The oxygen‐functionalized and Ni + x ( x= 2, 3)‐coordinated g‐C 3 N 4 produced 1664 μmol g −1 of hydrogen evolution from water under direct solar light irradiation in 4 h, which is 23 times higher than that over O−g‐C 3 N 4 . This significant enhancement results from the combined effects of large surface area, the formation of long‐life deep‐trap states, effective charge carrier separation, and extended visible light absorption. The separation and transport behavior of the charge carriers are investigated by photoluminescence, time‐resolved photoluminescence, photocurrent and Mott–Schottky measurements. Additionally, the interaction between Ni + x ( x= 2, 3) and O−g‐C 3 N 4 is studied by X‐ray photoelectron spectroscopy, X‐ray diffraction, and FTIR spectroscopy. The Ni + x ( x= 2, 3)/O−g‐C 3 N 4 photocatalyst shows remarkable reusability over a period of two months (six cycles). This study may provide a pathway to simultaneously overcome the challenges of low surface area and poor charge separation in g‐C 3 N 4 ‐based photocatalysts.