Core–Shell β-SiC@PPCN Heterojunction for Promoting Photo-Thermo Catalytic Hydrogen Production

Abstract

Solar hydrogen production by metal-free photocatalysts represents one of the important routes to realize a low-carbon energy system. Herein, the core−shell β-silicon carbide@potassium-doped polymeric carbon nitride (β-SiC@PPCN) heterojunction with β-SiC as a core and PPCN as a shell for photo-thermo catalytic hydrogen production is developed. With such a heterojunction, not only can the H−OH bond of absorbed water be activated, but also the migration of photogenerated carriers can be promoted due to the created internalelectric-field. Owing to the excellent photothermal conversion property of β-SiC, the temperature-dependent catalytic activity is also studied. The core−shell β-SiC@PPCN heterojunction can be run at an elevated temperature upon illumination, which enhances photoinduced electron− hole separation. Density functional theory calculations demonstrate that the elevated running temperature can activate absorbed water. Remarkably, the synergy of photocatalysis and thermocatalysis makes the core−shell β-SiC-50@PPCN heterojunction yield a photo-thermo catalytic hydrogen production rate as high as 13046.7 μmol• g −1 •h −1 . The present study provides a promising strategy for large-scale solar hydrogen production.

SiC Substrate/Pt Nanoparticle/Graphene Nanosheet Composite Photocatalysts for Hydrogen Generation

“…Figure e shows a comparison of the photocatalytic activity of SiC-based photocatalytic materials. First, the rate of pristine SiC photocatalyst’s hydrogen production was in the range of 2.68–11 μmol·g –1 ·h –1 , owing to the lack of active sites and the high recombination of charge–hole pairs of the pristine SiC photocatalyst. ,,, By doping SiC with the noble metal Pt, the hydrogen production rate has boosted at 204 μmol·g –1 ·h –1 . − Furthermore, by doping SiC with carbon materials, for instance, carbon nanowires, carbon nanotubes, graphene, carbon black, etc., the hydrogen production rate has sharply improved to 1328.4 μmol·g –1 ·h –1 . ,,,− In recent years, the hot photocatalytic material graphitic carbon nitride (g-C 3 N 4 ) and SiC form a composite photocatalyst, which can reach a hydrogen production rate of 595.3–2971 μmol·g –1 ·h –1 . − In the present work, SiC/Pt/graphene composite photocatalysts with stabilized heterojunctions between β-SiC, graphene, and Pt were prepared using the FJH process. Compared with the photocatalytic activity of pristine SiC, the SiC/Pt/graphene composite photocatalyst had a 175-fold increase achieving the maximum value of 2980 μmol·g –1 ·h –1 .…”

Preparation of Heterojunction Catalysts for Photocatalysis by in‐situ Synthesis: What We Should Do Next?

“…For example, Liao et al. developed the core–shell β‐silicon carbide (β‐SiC) on potassium‐doped polymeric carbon nitride (PPCN) heterojunction (β‐SiC@PPCN) with β‐SiC as a core and PPCN as a shell for photo‐thermo catalytic hydrogen production [51] . The heterostructure of this β‐SiC@PPCN was clearly observed by TEM coupled with EDS elemental mapping.…”

Efficient Nb2O5@g-C3N4 heterostructures for enhanced photocatalytic CO2 reduction with highly selective conversion to CH4

“…14,18,19 In recent years, the shortcoming was solved by creating semiconductor heterojunctions with a suitable band structure, which can greatly facilitate the separation and migration of photoinduced charges. 14,20–22 To date, heterojunction photocatalysts based on g-C 3 N 4 in abundance have been effectively designed to improve the photocatalytic activity, like g-C 3 N 4 /ZnFe 2 O 4 , 23 g-C 3 N 4 /Ag 3 VO 4 , 24 g-C 3 N 4 /CdS, 25 Bi 2 WO 6 /g-C 3 N 4 26 and so on. However, some of the above materials have obvious drawbacks such as poor stability, high production difficulty and high cost, which ultimately limit their practical application.…”