Amorphous Semiconductor Nanowires Created by Site-Specific Heteroatom Substitution with Significantly Enhanced Photoelectrochemical Performance

Abstract

Semiconductor nanowires that have been extensively studied are typically in a crystalline phase. Much less studied are amorphous semiconductor nanowires due to the difficulty for their synthesis, despite a set of characteristics desirable for photoelectric devices, such as higher surface area, higher surface activity, and higher light harvesting. In this work of combined experiment and computation, taking Zn2GeO4 (ZGO) as an example, we propose a site-specific heteroatom substitution strategy through a solution-phase ions-alternative-deposition route to prepare amorphous/crystalline Si-incorporated ZGO nanowires with tunable band structures. The substitution of Si atoms for the Zn or Ge atoms distorts the bonding network to a different extent, leading to the formation of amorphous Zn1.7Si0.3GeO4 (ZSGO) or crystalline Zn2(GeO4)0.88(SiO4)0.12 (ZGSO) nanowires, respectively, with different bandgaps. The amorphous ZSGO nanowire arrays exhibit significantly enhanced performance in photoelectrochemical water splitting, such as higher and more stable photocurrent, and faster photoresponse and recovery, relative to crystalline ZGSO and ZGO nanowires in this work, as well as ZGO photocatalysts reported previously. The remarkable performance highlights the advantages of the ZSGO amorphous nanowires for photoelectric devices, such as higher light harvesting capability, faster charge separation, lower charge recombination, and higher surface catalytic activity.

Grain‐Boundary‐Induced Drastic Sensing Performance Enhancement of Polycrystalline‐Microwire Printed Gas Sensors

“…To further understand the electronic properties of pZGO, the projected density of state (pDOS) plots for the two specific systems (pZGO and sZGO) are shown in Figure . Theoretical simulations reveal that pZGO has a lower bandgap than pristine sZGO, and the calculated bandgap of sZGO is ≈2.05 eV (Figure ), which is in agreement with previously reported theoretical values (2.0–2.1 eV) . A GB is introduced at the midgap state near the top of the valance band, which is relatively shallow.…”

Synthesis of Amorphous InSb Nanowires and a Study of the Effects of Laser Radiation and Thermal Annealing on Nanowire Crystallinity

“…Compared to crystalline semiconductor NWs, there have been limited investigations into amorphous NWs. This is most likely due to challenges in the synthesis of nanoscale amorphous materials [ 12 ]. The two main categories of amorphous semiconductors are: chalcogenide glasses which include elements of VI and their compounds, and the tetrahedrally bonded semiconductors which include , , and amorphous III-V compounds [ 13 ].…”

“…Though several techniques are available for the characterization of c - , experimental techniques that allow investigation of disordered amorphous ( a - ) are very limited. It is, therefore, important to develop an effective strategy for the synthesis of a - NWs, where the amorphous phase and band structure can be tailored to enable the use of these NWs for energy storage and conversion applications [ 12 ].…”

“…Due to absence of crystal quality constrains, such materials have structural flexibility and it becomes possible to construct materials with properties that cannot exist in the corresponding crystalline state [ 19 ]. It is also possible to heat-treat amorphous materials and convert them into a crystalline state, thus providing an economically viable route for the synthesis of crystalline semiconductors [ 12 ]. Since amorphous semiconductors are known to have high light absorption capability and high temperature coefficient of resistance, they are attractive in photoelectric and clean energy device applications [ 12 ].…”

New insight into the selective photocatalytic oxidation of RhB through a strategy of modulating radical generation

“…11,21 CdS quantum dots (QDs) respond sensitively to visible (Vis) light, 19 and amorphous TiO 2 (a-TiO 2 ) efficiently captures h + . 38,39 As the photogenerated h + is directly trapped by a-TiO 2 , the $OH radicals of higher oxidation activity would be decreased according to equation (eqn (3) and (4)), further, the photoinduced stability of CdS QDs and the conversion ratio of selective photooxidation would be improved during the photocatalytic oxidation. 40 Therefore, it is expected that CdS/a-TiO 2 composite could be more favorable for enhancing the effect of$O 2 À rather than the $OH with higher oxidation activity in the photooxidation.…”