# Heterogeneous Doping of Nanodiamond Grains with Exfoliated 2D NbSe2 Nanostructures for Highly Sensitive Ammonia Gas Sensors at Room Temperature

## TL;DR

A new hybrid material made of nanodiamond and niobium diselenide is developed for highly sensitive ammonia gas detection at room temperature.

## Contribution

The first report of a nanodiamond–NbSe2 hybrid for ammonia sensing with superior performance and stability.

## Key findings

- The ND–NbSe2 hybrid shows a 11.3% response to 100 ppm ammonia, outperforming pure ND and NbSe2.
- The hybrid exhibits faster response and recovery times (81.2 and 70.6 seconds) compared to individual components.
- The hybrid demonstrates excellent long-term stability for ammonia gas detection.

## Abstract

Herein, a first-time report details the development of
a heterogeneous
nanodiamond (ND) grain-niobium diselenide (NbSe2) hybrid
for room-temperature ammonia (NH3) gas sensing. Exfoliated
NbSe2 nanorods, potentially formed via sonochemical exfoliation,
exhibit semiconducting behavior with a band gap of 2.29 eV. The ND–NbSe2 hybrid demonstrates higher NH3 selectivity compared
to pristine NbSe2 and ND. This hybrid achieves a significantly
higher response of 11.3% with faster response and recovery times (81.2
and 70.6 s) than those of ND (5.9%) and NbSe2 (4.5%) at
a lower concentration of 100 ppm. Also, the stability of the as-fabricated
ND toward NH3 gas is exceptional when compared to that
of NbSe2. This explains the level of influence of ND on
the present ND–NbSe2 hybrid heterostructure. Moreover,
the heterojunction formation with a change in the resistivity of the
sample is involved in the sensing mechanism. This can be ascribed
to the correlation of energy gaps between the ND grains (4.43 eV)
and NbSe2 nanorods (2.29 eV), which promotes electron transportation
from the conduction band of NbSe2 to ND at the applied
voltage. In addition, the NbSe2–ND hybrids offer
excellent stability for long-term gas detection. Furthermore, it is
expected that this study will inspire the development of 2D-NbSe2–nanodiamond hybrid materials for advanced gas-sensing
applications.