Enhancing
the Charge Carrier Separation and Transport
via Nitrogen-Doped Graphene Quantum Dot-TiO2 Nanoplate
Hybrid Structure for an Efficient NO Gas Sensor
posted on 2020-03-05, 16:57authored byG. Murali, Maddaka Reddeppa, Ch. Seshendra Reddy, Seongmin Park, T. Chandrakalavathi, Moon-Deock Kim, Insik In
Herein,
we demonstrate the ultraviolet (UV) light activated high-performance
room-temperature NO gas sensor based on nitrogen-doped graphene quantum
dots (NGQDs)-decorated TiO2 hybrid structure. TiO2 employed in the form of {001} facets exposed rectangular nanoplate
morphology, which is highly reactive for the adsorption of active
oxygen species. NGQD layers are grown on TiO2 nanoplates
by graphitization of precursors via hydrothermal treatment. The decoration
of NGQDs on the TiO2 surface dramatically enhanced the
efficiency of gas and carriers exchange, charge carrier separation
and transportation, and oxygen vacancies, which eventually improved
the sensing performance. At room temperature, the TiO2@NGQDs
hybrid structure exhibited a response of 12.0% to 100 ppm NO, which
is 4.8 times higher compared to that of pristine TiO2 nanoplates.
The response of TiO2@NGQDs hybrid structure is further
upgraded by employing the ultraviolet light illumination and manipulating
the operating temperature. Under the UV (λ = 365 nm) illumination
at room temperature, the hybrid structure response escalated to ∼31.1%
for 100 ppm NO. On the other hand, the tailoring of working temperature
yielded a response of ∼223% at an optimum operating temperature
of 250 °C. The NO gas-sensing mechanism of TiO2@NGQDs
nanoplate’s hybrid structure sensors under UV illumination
and different working temperatures is discussed.