Controllable Fabrication of PdO‐PdAu Ternary Hollow Shells: Synergistic Acceleration of H₂‐Sensing Speed via Morphology Regulation and Electronic Structure Modulation

Abstract

DOE) have listed various indicator requirements for hydrogen sensors, [3][4][5][6] among which the response time is set as the most stringent target, because the rapid response speed is vital to initial leakage detection, thus avoiding serious safety issues. Specifically, DOE requires that the response time (t 90 , the time required for the signal change to reach 90% of the equilibrium value after H 2 is introduced) should be less than 1 s to 1 vol% H 2 for automotive hydrogen safety sensors. This strict requirement has become one of the biggest scientific challenges in the field of chemical hydrogen sensors. [6] In addition, the requirement for room temperature (RT) and ambient condition (in the presence of air and steam, etc.) detection is also important, which enables the low power consumption and Internet of Things (IoT) compatibility of the H 2 sensors. [7,8] Owning to the highly selective and reversible interactions with H 2 at room temperature, Pd has become one of the most widely used materials for H 2 sensing. [1,9,10] However, the application of Pd-based sensors also suffers from the serious problem of sluggish response. [9] In order to accelerate the sensing speed, several different methods have been developed, which can be mainly divided into two categories including the morphology regulation and H 2 absorption ability optimization. The idea of the first strategy is to increase the specific surface area of Pd nanostructures via controlling their sizes and morphology. [11][12][13] A larger specific surface area provides a greater amount of H 2 adsorption sites and thus reducing the response time to H 2 . [14] The second method is tailoring the energy landscape for H 2 adsorption, penetration, dissociation and desorption on Pd via chemical modulations, [15][16][17] especially through the alloying technique. [18][19][20] For example, it has been reported that the response time of PdAu alloy nanoparticles (NPs) to H 2 decreased proportionally from 25 to 5 s with the increase of the Au content from 0 to 25%. [19] Although great efforts and some achievements have been made to improve the response speed of H 2 sensors, it seems that the DOE requirement is still difficult to achieve. [9] In the present work, PdO-decorated PdAu ternary materials with hollow shell structure (named as PdO-PdAu HSs) are synthesized by a simple NaBH 4 -reduction process. [21] PdO-PdAu HSs have shown admirable H 2 -sensing performance with ultrafast room-temperature Designing ultrafast H 2 sensors is of particular importance for practical applications of hydrogen energy but still quite challenging. Herein, PdO decorated PdAu ternary hollow shells (PdO-PdAu HSs) exhibiting an ultrafast response of ≈0.9 s to 1% H 2 in air at room temperature are presented. PdO-PdAu HSs are fabricated by calcinating PdAu bimetallic HSs in air to form PdO-Au binary HSs, which are then partially reduced by NaBH 4 solution, forming PdO-PdAu HSs. This ternary hybrid material takes advantage of multiple aspects to synergistically accelerate the sensing spe...

Hydrogen-Induced Aggregation of Au@Pd Nanoparticles for Eye-Readable Plasmonic Hydrogen Sensors

“…Specifically, the response value rises mildly and is approximately proportional to [H 2 ] 0.60 in the concentration range of 500 ppm (limit of detection, LOD) to 0.5% H 2 (Figures S3 and S4). This result is consistent with Sievert’s law that describes the transformation of Pd into α-phase PdH x ( x denotes the amount of H atoms in Pd). , Then, the sensor response increases abruptly between 0.5% and 2% H 2 and finally get saturated with a further increase in the hydrogen concentration. This kind of S-shaped curve is basically in accordance with the α–β phase-transition behavior of Pd in hydrogen gas. , Moreover, it is interesting to note that all of the sensing processes, independent of the hydrogen concentration, are irreversible, i.e., the optical property remains almost unchanged when H 2 is changed back into air (Figure A).…”

“…This result is consistent with Sievert's law that describes the transformation of Pd into α-phase PdH x (x denotes the amount of H atoms in Pd). 41,42 Then, the sensor response increases abruptly between 0.5% and 2% H 2 and finally get saturated with a further increase in the hydrogen concentration. This kind of S-shaped curve is basically in accordance with the α−β phase-transition behavior of Pd in hydrogen gas.…”

Tuning the selectivity of benzene hydroalkylation over PdZn/HBeta catalysts: identification of lattice contraction and electronic properties

“…The results show that metal doping regulates the surface electronic properties of Pd, and the electron-rich Pd surface was successfully constructed. 28,29…”

Controllable Fabrication of Hg–Pd–PdO Heterostructures as Efficient Peroxidase Mimics for Carcinoembryonic Antigen Detection

“…Similarly, introducing their oxides also greatly enhanced the property of the noble metals. Qi et al verified that the decoration of PdO alters the electronic state of Pd and reduces the energy barrier for hydrogen diffusing . Xu’s reports indicated that PtOx could accelerate oxygen-containing species adsorption and intermediate desorption from the Pt/PtOx-containing electrocatalyst’s surface .…”

“…Qi et al verified that the decoration of PdO alters the electronic state of Pd and reduces the energy barrier for hydrogen diffusing. 9 Xu's reports indicated that PtOx could accelerate oxygen-containing species adsorption and intermediate desorption from the Pt/ PtOx-containing electrocatalyst's surface. 10 Kwak's group proved that PdOx plays a critical role in determining oxidation activity rather than the electronic properties of Pd.…”