Atomic Layer Deposition of MoSe₂ Nanosheets on TiO₂ Nanotube Arrays for Photocatalytic Dye Degradation and Electrocatalytic Hydrogen Evolution

Abstract

Herein, hierarchical MoSe2/1D TiO2 nanotube layer structure was successfully fabricated in a simple and fast fashion and its photocatalytic and electrocatalytic properties were assessed. The novelty of this work lies in the utilization of Atomic Layer Deposition (ALD) technique to deposit MoSe2 nanosheets on 1D TiO2 nanotube layers. The photoelectrochemical and photo-and electrocatalytic properties were explored and optimized as a function of the MoSe2ALD cycles.ALD allowed precise control on MoSe2 nanosheet size, and in turn, on the surface structure, which is pivotal for efficient catalysts. The MoSe2 nanosheets grew on both inner and outer 1D TiO2 nanotube surface mainly perpendicularly oriented, maximizing the exposed active edges, an essential aspect to fully exploit the MoSe2 photo-and electrochemical properties. Outstanding photo-and electrocatalytic activity were recorded in both dye organic pollutant degradation and hydrogen evolution reaction applications, respectively. The excellent photocatalytic and electrochemical activity stems from the synergy between tailored ALD loading of MoSe2 nanosheets on 1D TiO2 nanotubular structure with high surface/volume ratio, which provided fast electron transfer and easy access to the MoSe2 active edges, boosting the catalytic activity. 1.IntroductionHeterogeneous catalysis is pivotal process in a great number of industrial chemical technologies, environmental remediations, and also for renewable energy sources, such as fuel cells or hydrogen energy. [1][2][3][4] The importance of heterogenous catalysis continuously increases and correspondingly

Deposition of MoSe2 flakes using cyclic selenides

“…Instead, the binding energy of Mo 3d at 228.3 eV corresponding to MoSe 2 was used for this purpose. 25,26 As compared to the XPS results obtained in our previous work from the MoSe 2 deposited using selenides 1 and 3, 15 one must notice relevant differences: (i) the absence of chlorine residues (mainly present by Mo-Cl species) and (ii) the well-dened Se 3d doublet. Those differences suggested the absence of impurities (other chemical species) and complete ligand exchange reaction between selenide 6 and MoCl 5 resulting in a high purity as-deposited ALD MoSe 2 .…”

“…Due to the strong overlapping of C 1s signal with Se LMM, the binding energy scale was referenced to the binding energy of Mo 3d at 228.3 eV corresponding to MoSe 2 . 25,26 The deconvolution of the Mo 3d spectra included the use of eight components since Mo 3d has a strong overlapping with the Se 3s signal. From those, six components corresponded to the three spin-orbit splitting of Mo 3d, Mo 3d 5/2 and Mo 3d 3/2 , i.e.…”

Recent Progress in the Synthesis and Applications of Composite Photocatalysts: A Critical Review

“…Beside the UV counterpart, about 46% of visible and 48% infrared light accounts for the total solar spectrum. [20,21] A variety of wide and narrow band gap photocatalysts and their composites, such as SrTiO 3 , [22,23] TiO 2 , [24,25] ZnO, [26,27] BiVO 4 , [28,29] Bi 2 WO 6 , [30,31] Cu 2 O, [32] CdS, [33,34] r-GO, [35,36] g-C 3 N 4 , [4,[37][38][39] MoS 2 , [40,41] MoSe 2 , [42][43][44] WS 2 , [45][46][47] Fe 2 O 3 , [48,49] LaFeO 3 , [10,50] BiFeO 3 , [50,51] CulnS 2 , [52] copper chalcogenide, [53,54] double-layered hydroxides (LDH), [55,56] and semiconductor quantum dots, [57] etc., have been assessed so far in photocatalysis for water reduction, CO 2 conversion and pollutant degradation. Thus, a single semiconductor photocatalyst always exhibit low photocatalytic efficiency owing to the low solar energy harvesting and poor charge carrier's separation.…”

Organoselenium Precursors for Atomic Layer Deposition

“…The prepared MoSe 2 /1D TiO 2 nanotube heterostructures showed outstanding photo- and electrocatalytic activities for degradation of organic pollutants and hydrogen evolution reaction. 16 …”

“…By properly controlling the ALD process, 1D TiO 2 nanotube layers were also successfully covered by MoSe 2 by using bis­(trimethylsilyl)­selenide and MoCl 5 . The prepared MoSe 2 /1D TiO 2 nanotube heterostructures showed outstanding photo- and electrocatalytic activities for degradation of organic pollutants and hydrogen evolution reaction …”