Citation: Lin, R.; Hu, Q.; Liu, Z.;
Pan, S.; Chen, Z.; Zhang, W.; Liu, Z.;
Zhang, S.; Zhang, C. Integrated
CuO/Pd Nanospike Hydrogen
Sensor on Silicon Substrate.
Nanomaterials 2022, 12, 1533. https://
doi.org/10.3390/nano12091533
Academic Editors: Ki-Hyun Ki,
Deepak Kukkar and Sergei Kulinich
Received: 1 April 2022
Accepted: 29 April 2022
Published: 2 May 2022
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Article
Integrated CuO/Pd Nanospike Hydrogen Sensor on
Silicon Substrate
Ru Lin
1,2
, Qi Hu
1,3
, Zuolian Liu
1
, Shusheng Pan
1,3
, Zhifeng Chen
1
, Wei Zhang
1,3
, Zhiyu Liu
1
,
Shaolin Zhang
1,3,
* and Chengyun Zhang
1,3,
*
1
School of Physics and Materials Sciences, Guangzhou University, Guangzhou 510006, China;
rulinguangda@163.com (R.L.); 2112019060@e.gzhu.edu.cn (Q.H.); zuolian@gzhu.edu.cn (Z.L.);
sspan@gzhu.edu.cn (S.P.); chenzf@gzhu.edu.cn (Z.C.); wzhang@gzhu.edu.cn (W.Z.);
liuzhiyu@gzhu.edu.cn (Z.L.)
2
School of Electronics and Communication Engineering, Guangzhou University, Guangzhou 510006, China
3
Research Center for Advanced Information Materials (CAIM), Huangpu Research Graduate School,
Guangzhou University, Guangzhou 510555, China
* Correspondence: slzhang@gzhu.edu.cn (S.Z.); chyzhang@gzhu.edu.cn (C.Z.)
Abstract:
A large area of randomly distributed nanospike as nanostructured template was induced
by femtosecond (fs) laser on a silicon substrate in water. Copper oxide (CuO) and palladium (Pd)
heterostructured nanofilm were coated on the nanospikes by magnetron sputtering technology
and vacuum thermal evaporation coating technology respectively for the construction of a p-type
hydrogen sensor. Compared with the conventional gas sensor based on CuO working at high
temperature, nanostructured CuO/Pd heterostructure exhibited promising detection capability to
hydrogen at room temperature. The detection sensitivity to 1% H
2
was 10.8%, the response time was
198 s, and the detection limit was as low as 40 ppm, presenting an important application prospect in
the clean energy field. The excellent reusability and selectivity of the CuO/Pd heterostructure sensor
toward H
2
at room temperature were also demonstrated by a series of cyclic response characteristics.
It is believed that our room-temperature hydrogen sensor fabricated with a waste-free green process,
directly on silicon substrate, would greatly promote the future fabrication of a circuit-chip integrating
hydrogen sensor.
Keywords: femtosecond laser; hydrogen sensor; CuO; Pd; Si nanospike; green process
1. Introduction
As an important industrial chemical and green energy, hydrogen provides energy
support for global sustainable development. The production, transportation and storage
of hydrogen energy involve various fields, such as automobile, fuel cell, rocket engine,
chemical industry, aircraft, semiconductor manufacturing and metallurgy [
1
], which has
attracted extensive attention [
2
]. In addition, hydrogen can also be used effectively for
a variety of disease treatment and may play an important role in medical and biological
research in the future [
3
]. However, hydrogen is invisible, tasteless, and highly flammable
and explosive when the concentration of hydrogen in air is higher than 4%. Therefore, it
is necessary to manufacture sensors that can detect hydrogen leakage [
4
,
5
]. At present,
there are many types of hydrogen sensors based on electrochemistry [
6
], optics [
7
,
8
], sur-
face acoustic wave [
9
], catalysis [
10
,
11
], mechanics [
12
] nano resistance [
13
–
15
] and so on.
The semiconducting metal oxide sensor has become a promising candidate for hydrogen
detection due to its advantages of high sensitivity, low cost, abundance, chemical stability,
easy fabrication, and environmental protection [
1
]. For example, oxides of various metals
such as tungsten, titanium, zinc [
4
,
16
–
22
] are used in the constructions of hydrogen sensors.
Especially the hydrogen sensors based on CuO, a non-toxic and low-cost p-type semicon-
ducting metal oxide with a band gap of 1.2~1.9 eV, have attracted much attention [
23
–
25
].
Nanomaterials 2022, 12, 1533. https://doi.org/10.3390/nano12091533 https://www.mdpi.com/journal/nanomaterials
