Nickel as a co-catalyst for photocatalytic hydrogen evolution on graphitic-carbon nitride (sg-CN): what is the nature of the active species?

Abstract

The nature of a nickel-based co-catalyst deposited on a sol-gel prepared porous graphitic-carbon nitride (sg-CN), for photocatalytic H 2 production from water, has been investigated. The formation of the active catalytic species, charge separation and recombination of the photogenerated electrons and holes during photochemical H 2 evolution has been determined for the first time using in situ EPR spectroscopy.

Boosting Visible‐Light‐Driven Photocatalytic Hydrogen Evolution with an Integrated Nickel Phosphide–Carbon Nitride System

“…[11,25] The acquired rate was 3.3 times higher than our previously published work with the Ni 0 -sg-CN catalyst [4] and the activity is 54 %ofPt-sg-CN with similar Pt loading ( Figure S12). As photocatalytic activity of the catalyst largely depends on the irradiation area of the light, normalization is necessary to compare it with other reported systems.T he rate of H 2 production with 2I is 8400 mmol H 2 m À2 h À1 and thus comparable to other highly active CN-based catalysts.…”

“…Interestingly,during photochemical HER (e.g. [4] When the light was turned off,the Ni 0 signal was decreased rather fast but not completely ( Figure S26). In fact, this has been observed previously for the Ni 2+ -sg-CN system reported by us.…”

“…[1] Light-driven splitting of water to molecular O 2 and H 2 using photocatalysts is therefore apromising route for solar-to-chemical energy conversion. [4] So far, Pt has been widely utilized as co-catalyst with various semiconductors for the photocatalytic H 2 evolution reaction (HER). [4] So far, Pt has been widely utilized as co-catalyst with various semiconductors for the photocatalytic H 2 evolution reaction (HER).…”

“…[21] Although, H 2 evolution with pure g-CN is low, loading of suitable co-catalysts have shown to improve the activity significantly. [4] The remarkable features of hexagonal Ni 2 Pp rompted us to elucidate whether or not the HER activity can be boosted further by loading of Ni 2 Pasco-catalyst on sg-CN. [4] The remarkable features of hexagonal Ni 2 Pp rompted us to elucidate whether or not the HER activity can be boosted further by loading of Ni 2 Pasco-catalyst on sg-CN.…”

“…These values are typical for pure Ni 2 Pa nd exactly matching with other literature reports. [4] After the thorough characterizations,t he materials were tested for the photocatalytic HER in the presence of the sacrificial electron donor triethanolamine (TEOA) under visible light irradiation (> 420 nm). [24] TheN1s,C1s and O1s XPS spectra showed characteristic nature of carbon nitride and discussed in the SI ( Figure S11).…”