Ice‐Assisted Synthesis of Black Phosphorus Nanosheets as a Metal‐Free Photocatalyst: 2D/2D Heterostructure for Broadband H₂ Evolution

Abstract

enhanced activity both under λ > 420 nm and λ > 475 nm light irradiation and to long-term stability. The H 2 production rate of BP/g-C 3 N 4 (384.17 µmol g −1 h −1 ) is comparable to, and even surpasses that of the previously reported, precious metal-loaded photocatalyst under λ > 420 nm light. The efficient charge transfer between BP and g-C 3 N 4 (likely due to formed NP bonds) and broadened photon absorption (supported both experimentally and theoretically) contribute to the excellent photocatalytic performance. The possible mechanisms of H 2 evolution under various forms of light irradiation is unveiled. This work presents a novel, facile method to prepare 2D nanomaterials and provides a successful paradigm for the design of metal-free photocatalysts with improved chargecarrier dynamics for renewable energy conversion. solar fuel technology. For acquiring the above listed beneficial features, visible light-responsive graphitic carbon nitride (g-C 3 N 4 ), a 2D metal-free photocatalyst, has been extensively explored in photocatalysis. Though g-C 3 N 4 was discovered to be feasible for photocatalytic water splitting, obtaining a relatively high efficiency of H 2 production still largely relies on the loading of noble metal cocatalysts because of the high recombination rate of the charge carriers in g-C 3 N 4 . [2] Furthermore, the relatively wide bandgap (2.7 eV) confines its light response mainly into the ultraviolet (UV) range and only slightly into a narrow region of the visible light range (λ < 460 nm). [3] To solve these problems, numerous strategies have been developed, mainly including morphology tuning, doping with metal/nonmetal ions, and heterojunction creation. [4] However, quite limited progresses have been achieved thus far. Aiming to enhance the harvesting of solar light efficiently and economically, the development of novel g-C 3 N 4 -based metal-free photocatalysts with a broader photoresponse range is of great significance.Black phosphorus (BP), a layered material that consists of corrugated atomic planes with strong intralayer chemical bonding and weak interlayer van der Waals interactions, has attracted tremendous interest of material scientists. Since the PhotocatalysisThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Black Phosphorus‐Based Semiconductor Heterojunctions for Photocatalytic Water Splitting

“… a) Schematic illustration of the photogenerated carriers transfer pathways and mechanism of photocatalytic H 2 evolution. Reproduced with permission from reference . Copyright 2019, Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim.…”

“…Meanwhile, Ma et al. also exploited a facile, time‐effective ice‐assisted exfoliation method to prepare FBP nanosheets with high yield and fabricated a similar FBP/CN heterojunction for broadband photocatalytic H 2 evolution (Figure a) …”

Advances in 2D/2D Z‐Scheme Heterojunctions for Photocatalytic Applications

“…In addition to these metal‐containing 2D semiconductor photocatalysts, some metal‐free materials with 2D layered structure have also demonstrated good performance in photocatalysis, such as g‐C 3 N 4 , BP, and graphene. [ 108–112 ] Tri‐ s ‐triazine‐based g‐C 3 N 4 with a graphite‐like layered structure has attracted a lot of attention in photocatalysis, due to its high thermal and chemical stability, low cost, ease of preparation, and favorable energy band structure. However, its low specific surface area usually restricts its performance in photocatalysis.…”

The Art of Constructing Black Phosphorus Nanosheet Based Heterostructures: From 2D to 3D

“…BPNS heterostructures can also be formed by electrostatically assembling BPNSs with other 2D materials that have an opposite zeta potential in solvents. For example, numerous BPNS‐based heterostructures have been constructed by electrostatically assembling BPNSs with other 2D materials such as bismuth vanadate (BiVO 4 ), [ 112 ] graphitic carbon nitride (g‐C 3 N 4 ), [ 113 ] and MXene. [ 114 ] Ideally, highly ordered heterostructures can be obtained through the layer‐by‐layer assembly of differently charged nanosheets via electrostatic interactions.…”

“…Similarly, Ma and co‐workers synthesized a 2D/2D heterojunction of BPNS/g‐C 3 N 4 by assembling them in isopropanol and investigated their photocatalytic H 2 evolution performance. [ 113 ] Under λ > 420 nm light irradiation, BPNS/g‐C 3 N 4 showed a H 2 evolution rate of 384. 17 µmol g −1 h −1 , which is about 7 and 4.5 orders of magnitude higher than that of pristine BPNSs and g‐C 3 N 4 , respectively.…”