Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interface-Confined Doubly Anisotropic Oxidation of Two-Dimensional MoS2   Despite their importance, chemical reactions confined in a low dimensional
space are elusive and experimentally intractable. In this work, we report
doubly anisotropic, in-plane and out-of-plane, oxidation reactions of
two-dimensional crystals, by resolving interface-confined thermal oxidation of
a single and multilayer MoS2 supported on silica substrates from their
conventional surface reaction. Using optical second-harmonic generation
spectroscopy of artificially stacked multilayers, we directly proved that
crystallographically oriented triangular oxides (TOs) were formed in the
bottommost layer while triangular etch pits (TEs) were generated in the topmost
layer and that both structures were terminated with zigzag edges. The formation
of the Mo oxide layer at the interface demonstrates that O2 diffuses
efficiently through the van der Waals (vdW) gap but not MoO3, which would
otherwise sublime. The fact that TOs are several times larger than TEs
indicates that oxidation is greatly enhanced when MoS2 is in direct contact
with silica substrates, which suggests a catalytic effect. This study indicates
that the vdW-bonded interfaces are essentially open to mass transport and can
serve as a model system for investigating chemistry in low dimensional spaces.

33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol