Table 3.
Resume of best performances Pd NPs-based electrical hydrogen gas sensors found in the literature. Unless specified, the sensor response is obtained by the relation given in Equation (3). (*) Sensor response is given by the ratio of the resistance in air and in the hydrogenated environment. (**) Sensor response is given by the relative variation of conductance. (***) Sensor response is given by the relative variation of current intensity. (****) Sensor response is given by the relative variation of resistance defined as (RO − RH2)/RH2, where Ro is the base resistance of the sensor in air, and RH2 is the resistance measured in a H2-containing environment.
| Sensing Material | Limit of Detection | Response Time | Recovery Time | T° | Sensor Response | Ref. |
|---|---|---|---|---|---|---|
| Pd NPs | 1% | 1.2 s/1% | 10 s | RT | 96% (**) | [8] |
| Pd NPs | 0.1–1% | 3 s/0.1% | 31 s | 323 K | 15.40% | [6] |
| Pd NPs | few ppm | 0.7 s/2.2% | 10.2 s | RT | 600% (**) | [33] |
| Pd NPs/Si nanowires | nr | 5 s/1% | nr | RT | 3400% (***) | [91] |
| Pd NPs/Si nanowires | nr | 3 s/5% | nr | nr | nr | [92] |
| Pd NPs/SnO2 | 10 ppm | 4 s/0.3% | 10 s | 473 K | 315.34 (*) | [49] |
| Pd NPs/SnO2 | 4.5 ppm | ~9 s/0.01% | ~9 s | 553 K | 8.2 (*) | [50] |
| Pd NPs/WO3 | ~1 ppm | 1.8 s/3% | nr | 423 K | 3.14 × 106 (*) | [52] |
| Pd NPs/WO3 | 40 ppm | 120 s/0.05% | 12 min | 473 K | 103 (*) | [51] |
| Pd NPs/WO3 | 10 ppm | 10 s/0.005% | 50 s | 403 K | 382 (*) | [93] |
| Pd NPs/WO3 | <500 ppm | 7 s/2% | nr | RT | 230 (*) | [53] |
| Pd NPs/WO3 | nr | <1 s/2% | 50 | 353 K | >104(****) | [73] |
| Pd NPs/ZnO | <0.5 ppm | 18.8 s/0.1% | nr | RT | 91.2% | [47] |
| Pd NPs/MnO2 | 10 ppm | 4 s/0.01% | ~20 min | 373 K | 11.5 (*) | [63] |
| Pd NPs/MoS2 | 50 ppm | 780 s/1% | ~15 min | RT | 35.3% | [72] |
| Pd NPs/SWCNTs | 10 ppm | 7 s/1% | nr | RT | 25% | [48] |
| Pd NPs/SWCNTs | 250 ppm | 5 s/2.5% | nr | RT | nr | [94] |
| Pd NPs/SWCNTs | 100 ppm | 3 s/1% | 5 min | RT | 130% | [75] |
| Pd NPs/Graphene | 0.2 ppm | ~240 s/0.1% | ~600 s | RT | 7% | [74] |
| Pd NPs/Graphene | 200 ppm | 6 s/2% | 45 s | RT | 51% | [39] |
| Pd Ncubes/Graphene | 6 ppm | nr | nr | 323 K | 10.4% | [67] |
| Pd NPs/CNTs | <5 ppm | ~30 s/0.1% | ~3 min | RT | ~7.3% | [68] |
| PdNi NPs/Graphene | <10 ppm | 180 s/0.1% | 720 s | RT | 11% | [78] |
| PdPt NPs/Graphene | nr | < 2 s/2% | 18 s | 313 K | 4% | [83] |
| Pd@Pt NPs/ZnO nanorods | 0.2 ppm | 5 s/1% | 76 s | 373 K | 58% | [55] |
| Pd@Pt NPs/Si nanowires | <10 ppm | 7.7 s/1% | 7.7 s | 348 K | 5.02% | [82] |
| Pd NPs/C nanowires | 10 ppm | < 70 s/10 ppm- 1% | 5 s | RT | 175% | [69] |
| Pd NPs in Nafion | ~0.2% | 10 s/nr | nr | RT | nr | [76] |