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10.1002/anie.201903027
Angewandte Chemie International Edition
COMMUNICATION
Novel 2D Layered Zinc Silicate Nanosheets with Excellent
and CO2 Conversion
Lan Wang,* Detlef W. Bahnemann, Liang Bian, Guohui Dong, Jie Zhao, and Chuanyi Wang*
Abstract: Two-dimensional (2D) photocatalysts are highly attractive
for their great potential in environmental remediation and energy
conversion. Herein, we report a novel layered zinc silicate (LZS)
photocatalyst synthesized via liquid-phase epitaxial growth route
using silica derived from vermiculite, a layered silicate clay mineral,
as both lattice-matched substrate and Si source. The epitaxial
growth of LZS is limited in the 2D directions, thus generating the
vermiculite-type crystal structure and ultrathin nanosheet
morphology with thicknesses of 8~15 nm and lateral size of about
200 nm. Experimental observations and density functional theory
(DFT) calculations evince that LZS has a superior band alignment
Scheme 1. Schematic illustration of liquid-phase epitaxial growth of LZS
nanosheets in hydrothermal condition.
for degradation of organic pollutants and reduction of CO2 to CO.
These nanosheets exhibit efficient photocatalytic performance for 4-
chlorophenol (4-CP) degradation and CO2 conversion to CO, ca.
2.9-fold and 3-fold higher than commercial P25 under UV-vis light,
travel distance of the photoexcited carriers, abundant surface
respectively. The present work gives the first example of clay-like 2D
active sites, and interlayer space for hybridization with other
photocatalyst with strong photooxidation and photoreduction
species[6], all of which are beneficial to photocatalytic reactions
compared with the powdered photocatalysts.
capabilities.
Layered silicates as typical 2D inorganic materials were
Semiconductor photocatalysis is considered to be one of the
most promising and practical solutions to address current and
future energy and environmental concerns.[1] Since the
discovery of water-splitting system based on titanium dioxide
(TiO2) under light irradiation,[2] various inorganic materials have
been explored as catalysts for photocatalysis, aiming to produce
widely used as catalyst supports as well as adsorbents, owing to
their low cost and abundant reserves.[7] So far, however, the
photocatalytic properties of these materials have been mostly
ignored due to their photo-inert in nature. For natural layered
silicates, such as clay minerals (e.g., vermiculite, montmorillonite,
etc.), their crystal structure consists of layers made up of two
silicon-oxygen tetrahedra sheets fused to an edge-shared
octahedral sheet of either aluminum or magnesium hydroxide.[8]
Indeed, they have no photocatalytic activity under UV irradiation.
With the consideration that the synthetic layered silicates can be
incorporated with transition metals in the octahedral position,
metal silicates with layered structure will be envisioned as
providing the opportunity of having silicate-based photocatalysts.
ZnO as a wide band gap semiconductor has been widely
used in the photocatalytic degradation. From a crystallographic
point of view, Zn(II) can be incorporated into the octahedral
framework of silicates.[9] Moreover, Zn-type layered double
hydroxides (e.g. ZnAl LDH, ZnCr LDH and ZnTi LDH), a known
class of anionic clays, have been used as photocatalysts for
reduction of CO2,[10] and degradation of organic dyes and
pesticides,[11] respectively. We expect that the structure and
performance advantages of LDH derived from zinc can be
applied to the clay-type 2D layered silicates material.
Accordingly, when the transition metal Zn(II) is present in well-
defined structural position, the obtained layered zinc silicate is
expected to overcome the instability of ZnO in aqueous system
and retain its photocatalytic activity. In many cases, however,
H2 and O2 from water,[3] produce hydrocarbon fuels through the
4]
conversions of CO2 with H2O,[1b,
and eliminate organic
pollutants.[5] Among various inorganic photocatalysts, two
dimensional (2D) nanosheet-shaped materials as novel
photocatalysts, particularly those having layered structure, have
been of great interest due to their diverse morphological
advantages such as high surface-to-volume ratio, relatively short
[*]
Dr. L. Wang, Laboratory of Environmental Sciences and
Technology, Xinjiang Technical Institute of Physics & Chemistry;
Key Laboratory of Functional Materials and Devices for Special
Environments, Chinese Academy of Sciences, Urumqi 830011,
China
E-mail: wanglan@ms.xjb.ac.cn
Prof. C.Y. Wang, Dr. G.H. Dong, Dr. J. Zhao, School of
Environmental Science and Engineering, Shaanxi University of
Science and Technology, Xian 710021, China
E-mail: cywang@ms.xjb.ac.cn
Prof. D. W. Bahnemann, Laboratorium fur Nano- und
Quantenengineering, Leibniz Universität Hannover, Schneiderberg
39, 30167 Hannover, Germany
Dr. L. Bian, Key Laboratory of Solid Waste Treatment and Resource
Recycle, South West University of Science and Technology,
Mianyang 621010, China
the
presence
of
non-homogenous
nanometer-scale
morphology and the high concentration of crystalline impurities
Supporting information for this article is given via a link at the end of
the document.
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