Unraveling Photoexcited Charge Transfer Pathway and Process of CdS/Graphene Nanoribbon Composites toward Visible‐Light Photocatalytic Hydrogen Evolution

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.201902459. 1-10 wt% GNRs, the CdS/GNR composites with 2 wt% GNRs achieves the greatest hydrogen evolution rate of 1.89 mmol h −1 g −1 . The corresponding apparent quantum efficiency is 19.3%, which is ≈3.7 times higher than that of pristine CdS NPs. To elucidate the underlying photocatalytic mechanism, a systematic characterization, including in situ irradiated X-ray photoelectron spectroscopy and Kelvin probe measurements, is performed. In particular, the interfacial charge transfer pathway and process from CdS NPs to GNRs is revealed. This work may open avenues to fabricate GNR-based nanocomposites for solar-to-chemical energy conversion and beyond.

Rapid Microwave‐Assisted Synthesis of CdS/Graphene/MoSx Tunable Heterojunctions and Their Application in Photocatalysis

“…The holes are consumed through the utilization of a sacrificial agent (oxalic acid), which is oxidized and heals the electronic deficiency in the valence band of the semiconductor. Thus, the photoexcited electrons escape from the bound state of excitons, through the conjugated network of rGO component . With MoS x nanoparticles anchored on graphitic sheets, the electron transfer takes place from graphene network to MoS x nanoparticles, driven by the band energy characteristics of the components .…”

“…In addition, due to the more positive potential of MoS x conduction band, the latter nanostructure may directly accept electrons from the CdS conduction band . As for the catalytic activity, both heteroatom‐doped graphene and MoS 2 components are expected to act as efficient catalytic sites for the photoreduction of 4‐nitrophenol …”

3D Graphene‐Based H2‐Production Photocatalyst and Electrocatalyst

“…A similar conclusion has been drawn by the same group for hierarchical CdS/graphene nanoribbons (GNRs) and Zn 0.5 Cd 0.5 S@polyacrylonitrile composite photocatalysts applied for HER. [ 93,94 ] Most recently, we employed a solution‐based hydrothermal growth technique to fabricate a hierarchical NiCo 2 O 4 /3D NGF framework (NCO/NGF). [ 95 ] The 3D NGF effectively imparted the composite with large specific surface area (155 m 2 g −1 ) and large pore volume.…”

“…Such function was further proved by the in situ X‐ray photoelectron spectroscopy (XPS) analysis (XPS test under illumination from light emitting diode (LED) source). [ 93 ] As shown in Figure 22 a,b, both the Cd 3d and S 2p XPS spectra of CdS/GNR2 (with a GNR content of 2 wt%) present a slightly positive shift (≈0.1 eV) compared to the pristine CdS. In view of the fact that the Fermi level of CdS is close to its CB position and is higher than that of the GNRs, the photogenerated electrons of CdS can transfer to the GNRs side at lower energy level.…”

A Novel Earth‐Abundant W‐WC Heterojunction as Efficient Co‐Catalyst for Enhanced Photocatalytic H2Evolution

“…[1][2][3] Photocatalytic hydrogen (H 2 ) production via semiconductor is considered to be one of ideal alternative technology for fossil fuels as this approach is clean and recycling. [4][5][6][7][8] However, the low efficiency of the bare semiconductor limits the industrialization of the photocatalytic H 2 evolution. Suitable co-catalyst loaded on semiconductor can provide more active sites, reduce the over-potential, inhibit the electron-hole pair recombination, and thus greatly increase the photocatalytic H 2 evolution activity.…”