# Research Progress of Gas Sensor Based on Graphene and Its Derivatives: A Review
## 6 Future Perspective  
The future of graphene in the field of gas detection is undoubtedly very broad. Due to the advantages in sensitivity, selectivity and small-size, graphene gas sensors have a good application prospect in industrial and agricultural production, and environmental monitoring. For example, graphene gas sensors can detect the breakdown products of SF\({}_{6}\), which is meaningful for gas insulating \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**No.** & **Material** & **Target Gas** & **Sensitivity** & **LOD** & **Response Time** & **Year** & **Reference** \\ \hline
1 & CVD Gr & H\({}_{2}\) & \(-\) & \(-\) & 11.8 s & 2015 & [60] \\ \hline
2 & MPCVD Gr & NO\({}_{2}\) & 1141\% & 785 ppt & 2 s & 2016 & [61] \\ \hline
3 & CVD Gr & NO\({}_{2}\) & \(\Delta\)I \(\approx\) 26 nA & 200 ppm & 67 s & 2016 & [62] \\ \hline \multirow{2}{*}{4} & \multirow{2}{*}{CVD Gr} & NH\({}_{3}\) & \(9.3\times 10^{-5}\) ppm\({}^{-1}\) & 17 ppm & 10 min & \multirow{2}{*}{2017} & [63] \\ \cline{3-4}  & & NO\({}_{2}\) & 0.024 ppm\({}^{-1}\) & 0.24 ppm & 10 min & & \\ \hline
5 & r-GO & DMMP & \(\Delta\)R/R\({}_{0}\) \(>\) 10\% & 50 ppm & 150 s & 2017 & [64] \\ \hline
6 & CVD Gr & methane & 0.344 nm\(\%^{-1}\) & 3.5 vol \% & 50 s & 2017 & [65] \\ \hline
7 & CVD Gr & NH\({}_{3}\) & \(\Delta\)R/R\({}_{0}\) = 4.9\% & 18.8 sccm & 70 s & 2017 & [66] \\ \hline
8 & F-Gr & NH\({}_{3}\) & \(\Delta\)R/R\({}_{0}\) = 3.8\% & 2 ppm & 30 s & 2016 & [73] \\ \hline
9 & CVD-Gr & NO\({}_{2}\) & \(\Delta\)I \(\approx\) 0.0025 A & 0.12 ppm & 4 min & 2017 & [74] \\ \cline{3-4}  & LPE-Gr & & \(\Delta\)I \(\approx\) 0.0020 A & 0.45 ppm & 4 min & 2017 & [74] \\ \hline
11 & Pd-PANI-rGO & H\({}_{2}\) & \(\Delta\)R/R\({}_{0}\) = 25\% & 1 vol \% & 20 s & 2016 & [78] \\ \hline
12 & rGO-ZnO & NO\({}_{2}\) & \(\Delta\)R/R\({}_{0}\) = 25.6\% & 5 ppm & 165 s & 2014 & [83] \\ \hline
13 & CuO-ZnO/rGO & acetone & \(\rm R_{g}/R_{a}\) = 1.5 & 10 ppm & & 2014 & [84] \\ \hline
14 &
\begin{tabular}{c} Ni-doped \\ SnO\({}_{2}\)/GO \\ \end{tabular} & acetone & \(\Delta\)G/C\({}_{0}\) = 27.5\% & 200 ppm & 5.4 s & 2015 & [85] \\ \hline \multirow{2}{*}{15} & \multirow{2}{*}{GO-SnO\({}_{2}\)} & ethanol & \(\rm R_{a}/R_{t}\) = 160 & \multirow{2}{*}{200 ppm} & \multirow{2}{*}{\(-\)} & \multirow{2}{*}{2017} & [88] \\ \cline{3-4}  & & acetone & \(\rm R_{a}/R_{t}\) = 200 & & & \\ \cline{3-4}  & & formaldehyde & \(\rm R_{a}/R_{t}\) = 91 & & & \\ \hline \multirow{2}{*}{16} & AgNPs-rGO & \multirow{2}{*}{NH\({}_{3}\)} & \(\Delta\)R/R\({}_{0}\) = 6.52\% & \multirow{2}{*}{1 ppm} & 70 s & \multirow{2}{*}{2017} & [89] \\ \cline{3-4}  & PtNPs-rGO & & \(\Delta\)R/R\({}_{0}\) = 2.87\% & \multirow{2}{*}{1 ppm} & 80 s & \multirow{2}{*}{2017} & [89] \\ \cline{3-4}  & AuNPs-rGO & & \(\Delta\)R/R\({}_{0}\) = 0.5\% & & 100 s & & \\ \hline
17 & ZnO-Gr & NO\({}_{2}\) & \(\Delta\)R/R\({}_{0}\) = 12.57\% & 1 ppm & 250 s & 2017 & [90] \\ \hline
18 & ZnO NW-rGO & NH\({}_{3}\) & \(\Delta\)R/R\({}_{0}\) = 19.2\% & 50 ppm & 100 s & 2017 & [91] \\ \hline
19 & ZnO-rGO & chloroform vapor & \(\Delta\)R/R\({}_{0}\) = 1.75\% & 20 ppm & 10 s & 2017 & [92] \\ \hline
20 & TiO\({}_{2}\)-rGO & NH\({}_{3}\) & \(\Delta\)R/R\({}_{0}\) = 1.7 & 10 ppm & 114 s & 2017 & [94] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Typical gas sensors based on graphene materials. of electrical equipment [63]. However, the current large-scale application of graphene still has difficulties. There are two main bottlenecks. Firstly, there is no method for large-scale preparation of graphene gas sensors. Secondly, graphene needs to be further treated to improve its response sensitivity to specific gases. Judging from the current development trend, the improvement of response time may be from the following aspects: (1) increasing specific surface area by modifying surface and compositing with other nanomaterials specifically; and (2) designing appropriate structure.