ppb-Level Selective Hydrogen Gas Detection of Pd-Functionalized In2O3-Loaded ZnO Nanofiber Gas Sensors

Abstract

Pd nanoparticle-functionalized, xIn2O3 (x = 0.05, 0.1, and 0.15)-loaded ZnO nanofibers were synthesized by an electrospinning and ultraviolet (UV) irradiation method and assessed for their hydrogen gas sensing properties. Morphological and chemical analyses revealed the desired morphology and chemical composition of the synthesized nanofibers. The optimal gas sensor namely Pd-functionalized, 0.1In2O3-loaded ZnO nanofibers showed a very strong response to 172–50 ppb hydrogen gas at 350 °C, which is regarded as the optimal sensing temperature. Furthermore, the gas sensors showed excellent selectivity to hydrogen gas due to the much lower response to CO and NO2 gases. The enhanced gas response was attributed to the excellent catalytic activity of Pd to hydrogen gas, and the formation of Pd/ZnO and In2O3/ZnO heterojunctions, ZnO–ZnO homojunction, as well as the formation of PdHx. Overall, highly sensitive and selective hydrogen gas sensors can be produced based on a simple methodology using a synergistic effect from Pd functionalization and In2O3 loading in ZnO nanofibers.

1D Metal Oxide Semiconductor Materials for Chemiresistive Gas Sensors: A Review

“…fabricated a ppb‐level hydrogen sensor based on Pd‐functionalization In 2 O 3 ‐ZnO nanofiber nanostructure. [ 248 ] A systematic gas sensing analysis was reported in Figure . 0.1 In 2 O 3 ‐loaded on ZnO nanofiber nanostructures had the highest response to hydrogen in the samples without Pd.…”

“…This enhanced sensing performance is attributed to the mismatch in the Fermi energy level between In 2 O 3 and ZnO which results in a potential barrier for the flow of electrons and a decrease of resistance when exposed to analyte, electronic sensitization effect and chemical sensitization effect of Pt of which allows oxygen molecules into the Pt surrounding surface, and defects in sensing material. [ 245,246,248,249 ]…”

“…combined electrospinning and hydrothermal methods to synthesis sensing materials of MoS 2 /SnO 2 heterojunctions which were further used to fabricate sensors for detection of TMA. [ 248 ] The optimum temperature of MoS 2 /SnO 2 is 230 °C, while pure SnO 2 is 270 °C. Response ( R a / R g ) of MoS 2 /SnO 2 is 106.3 toward 200 ppm TEA, which is around 11 times higher than pristine samples.…”

Recent Advances and Challenges of Nanomaterials-Based Hydrogen Sensors

“…In 2019, Lee et al and their team investigated the heterojunction gas sensor based on Pd-functionalized In 2 O 3 -loaded ZnO nanofiber and synthesized by electrospinning and an ultraviolet irradiation method for hydrogen sensing applications [141]. Besides the hydrogen active Pd NPs, the sensor also employed heterojunctions like In 2 O 3 /ZnO, homojunctions like ZnO-ZnO and In 2 O 3 -In 2Tablw O 3 , and the Schottky junction Pd/ZnO, which all contribute to improved gas sensing performance.…”

“…This process significantly affects the potential heterojunction barriers and dramatically improves the range of resistance modulation in the ZnO-SnO2 heterojunction. In 2019, Lee et al and their team investigated the heterojunction gas sensor based on Pd-functionalized In2O3-loaded ZnO nanofiber and synthesized by electrospinning and an ultraviolet irradiation method for hydrogen sensing applications [141]. Besides the hydrogen active Pd NPs, the sensor also employed heterojunctions like In2O3/ZnO, homo-Figure 33.…”