Nanoscale Multidimensional Pd/TiO2/g-C3N4 Catalyst for Efficient Solar-Driven Photocatalytic Hydrogen Production

Abstract

Solar-to-fuel conversion is an innovative concept for green energy, attracting many researchers to explore them. Solar-driven photocatalysts have become an essential solution to provide valuable chemicals like hydrogen, hydrocarbon, and ammonia. For sustainable stability under solar irradiation, titanium dioxide is regarded as an acceptable candidate, further showing excellent photocatalytic activity. Incorporating the photo-sensitizers, including noble metal nanoparticles and polymeric carbon-based material, can improve its photoresponse and facilitate the electron transfer and collection. In this study, we synthesized the graphitic carbon nitride (g-C3N4) nanosheet incorporated with high crystalline TiO2 nanofibers (NF) as 1D/2D heterostructure catalyst for photocatalytic water splitting. The microstructure, optical absorption, crystal structure, charge carrier dynamics, and specific surface area were characterized systematically. The low bandgap of 2D g-C3N4 nanosheets (NS) as a sensitizer improves the specific surface area and photo-response in the visible region as the incorporated amount increases. Because of the band structure difference between TiO2 and g-C3N4, constructing the heterojunction formation, the superior separation of electron-hole is observed. The detection of reactive oxygen species and photo-assisted Kelvin probe microscopy are conducted to investigates the possible charge migration. The highest photocatalytic hydrogen production rate of Pd/TiO2/g-C3N4 achieves 11.62 mmol·h−1·g−1 under xenon lamp irradiation.

Design and Architecture of P-O Co-Doped Porous g-C3N4 by Supramolecular Self-Assembly for Enhanced Hydrogen Evolution

“…FT-IR measurements were conducted to further illustrate the chemical composition of the as-prepared samples, the results are shown in Figure 2. In the spectrum of the CN, there are a series of peaks in the range of 1200~1600 cm −1 , which are related to the stretching modes of CN heterocycles [3,48]. In addition, the sharp peak appeared at 810 cm −1 correspond to the bending vibrations of heptazine rings [3,48].…”

“…In the spectrum of the CN, there are a series of peaks in the range of 1200~1600 cm −1 , which are related to the stretching modes of CN heterocycles [3,48]. In addition, the sharp peak appeared at 810 cm −1 correspond to the bending vibrations of heptazine rings [3,48]. In the FT-IR spectra of the other three samples, the characteristic vibrational peak of CN heterocycles and heptazine rings could also be observed, suggesting that element doping will not destroy the structural integrity of g-C 3 N 4 .…”

“…In recent years, the excessive consumption of fossil fuel has brought a series of severe environmental problems, thus it is very urgent to develop and utilize environmentally friendly and clean energy at present [1,2]. In the past decades, photocatalytic hydrogen production utilizing solar energy was considered to be a huge potential strategy for hydrogen generation [3][4][5]. It was reported that metal-free polymeric graphitic carbon nitride (i.e., g-C 3 N 4 ) possessed good visible light response activity, suitable position, and chemical stability, and thus can be a candidate for substituting the traditional expensive metal-based photocatalysts [6,7].…”

“…Since 2009, Wang and co-researchers found that g-C 3 N 4 photocatalyst could split water to produce hydrogen under visible light [8]. Research about g-C 3 N 4 -based catalysts for photocatalytic hydrogen production is emerging and will continue to be attractive [3,4,9,10] in the coming years. Nevertheless, the bulk g-C 3 N 4 still has the following defects [9,10]: (1) small specific surface area; (2) scarce reaction active site; (3) insufficient visible light absorption (λ < 460 nm) ability and low quantum efficiency; and (4) high recombination rate of photo-generated electrons and holes.…”

Synthesizing the High Surface Area g-C3N4 for Greatly Enhanced Hydrogen Production

“…Graphite carbon nitride (g-C 3 N 4 ), which is the most stable allotrope of carbon nitride, has triggered broad interest due to its many fascinating properties, namely superior thermal and chemical stability, an appropriate direct band gap of 2.7 eV, and its low cost due to its abundant existence. These advantages lead to several applications such as CO 2 reduction [12][13][14][15], water splitting [16][17][18][19], organic pollution degradation [20][21][22], etc. However, obtained bulk g-C 3 N 4 prepared via the common thermal polymerization method has suffered from multiple drawbacks from achieving high activity, such as its small specific surface area and high charge recombination rate [23].…”