Modulating the 0D/2D Interface of Hybrid Semiconductors for Enhanced Photoelectrochemical Performances

Abstract

Despite major progress, these materials still face several significant challenges. In particular: 1) metal oxides usually possess a large bandgap that limits the sunlight absorption, 2) not all metal oxides have a favorable band alignment to realize both redox processes (water reduction and oxidation), 3) low electrical conductivity and limited hole diffusion length, 4) charge recombination can occur easily in the bulk and on the surface, limiting the efficiency of the system.Recently, extensive efforts have been made to explore non-oxide nanomaterials, such as metal chalcogenides (MoS 2 , CdS, etc.), and metal-free photocatalysts (g-C 3 N 4 , etc.) to enhance PEC activity thanks to their small bandgap, that allows to harvest a wide range of the solar spectrum. [4] On the other hand, the fabrication of heterojunction structures is considered as a promising approach to improve PEC performance [5] due to several advantages: 1) extension of the light absorption range; 2) effective separation of electron-hole pairs; 3) reduction of the recombination of photogenerated carriers.Heterostructure based on 0D/2D interfaces are particularly interesting due to the possibility of easily construct intimate interfaces. Among a wide gamut of 0D/2D heterostructure, quantum dots (QDs)/ 2D nanosheets (NSs) are promising for enhancing photoexcited electron/hole transfer due to their high charge mobility. [6] In a QDs/NSs heterostructure, a very intimate interface between the two is created, and since processes such as exciton dissociation and charge injection are critically dependent on the QD-surface distance, they will be enhanced. [7] Further, the presence of a 2D material can provide several superior features (compared to 0D and 1D nanomaterials) such as a significant increase of the material surface area, extended contact between the assembly and the electrolyte, and most remarkably, preferential electrical transport that can suppress charge carrier recombination and overall improve the functional PEC properties. [4a,8] Based on these advantages, the 0D/2D hybrid can combine the strong light harvesting capability of QDs with the catalytic performance of 2D platform.Here we describe the design and fabrication of a 0D/2D heterostructure based on a nanoflower-like hierarchical MoS 2 NSs assembly and on metal chalcogenide QDs, such as PbS, CdS, and their composite, PbS@CdS. MoS 2 is a widely studied Photoelectrochemical (PEC) solar-driven hydrogen production is a promising route to convert solar energy into chemical energy using semiconductors as active materials. However, the performance is still far from satisfactory due to a limited absorption range and rapid charge recombination. Compared to 3D semiconductors, 0D/2D nanohybrids may exhibit better PEC performance, due to the formation of an intimate interface between the two semiconductors that can inhibit carrier recombination. Herein, a photoelectrode based on a 0D/2D heterojunction is constructed by 0D metal chalcogenide quantum dots (QDs) and hierarchical 2D Zn-MoS 2 nanos...

A high-responsivity CsPbBr3 nanowire photodetector induced by CdS@CdxZn1−xS gradient-alloyed quantum dots

“…It has been demonstrated that the performance of photodetectors is significantly improved by integrating QDs as light-absorbing layers or active layers. [21][22][23][24][25][26]72 In addition, high-performance photodetectors decorated by QDs are also attracting increasing attention thanks to their great lightharvesting abilities and charge transfer characteristics. [27][28][29]46 As an example, Bi et al demonstrated that the photocurrent of a ZnO NWs device was enhanced from 0.167 to 1.84 mA by decorating binary CdS QDs.…”

Modulation of photogenerated holes for enhanced photoelectrocatalytic performance

“…The consumption of holes can ensure that the subsequent holes continue to migrate and improve the PEC efficiency. Commonly used sacrificial agents in PEC systems include Na 2 S-Na 2 SO 3 [20,21] , triethanolamine (TEOA) [22,23] and H 2 O 2 [24][25][26] and these have been widely used to evaluate interfacial charge transfer properties. Thorne et al measured the photocurrent-voltage curves of a hematite photoanode and found that the photoanode with H 2 O 2 as hole scavengers has lower onset potential values [24] .…”

Anchoring 0D CeO2 Nanoparticles on 2D LaTiO2N Nanosheets for Efficient Visible‐Light‐Driven Photocatalytic CO2 Reduction

“…Recently, 0D/2D heterojunctions have attracted much attention because of their excellent interfacial charge transfer characteristics [33–35] . Specifically, 0D nanoparticles have shorter charge transfer distances, and 2D nanosheets as carriers can avoid the self‐aggregation of 0D nanoparticles, which can provide more migration paths for the effective separation of photogenerated charge carriers [36,37] . Inspired by this, exploring an appropriate 0D semiconductor to compound with 2D LaTiO 2 N is expected to further improve the photocatalytic CO 2 reduction activity of LaTiO 2 N.…”