Welcome Lunch for Su-Ho at Eureka! in Irvine, Feb. 2, 2018. Clockwise from lower left: Christine, Gaurav, Josh, Prof. Il-Doo, Shaopeng, Apurva, Su-Ho, Ray-man, Alana, Reg, Annee, Eric, Ilektra. (missing: Vivian, Hiro, Thien).

Hollow Pd-Ag Composite Nanowires for Fast Responding and Transparent Hydrogen Sensors

Ji-Soo Jang, Shaopeng Qiao, Seon-Jin Choi, Gaurav Jha, Alana F. Ogata, Won-Tae Koo, Dong-Ha Kim, Il-Doo Kim* and Reginald M. Penner*,
ACS Appl Mater Inter 9 (2017) 39464.

Ji-Soo Jang, a visiting student from KAIST in Korea, developed and demonstrated a fabrication process for preparing hollow Pd-Ag alloy nanowires by using the electrodeposition of lithographically patterned silver nanowires, followed by galvanic replacement reaction (GRR) to form palladium. By controlling the GRR time of aligned Ag NWs within an aqueous Pd2+-containing solution, Pd@Ag HNWs were spontaneously obtained from Ag NWs, with control of the Pd:Ag stoichiometry. A GRR duration of 17 h transformed Ag NWs into Pd@Ag HNWs that showed enhanced H2 response and faster sensing response time compared with Ag NWs subjected to a GRR duration of 10 h.

Going Away Lunch for Hee-Jin. Somewhere in Irvine, Dec. 18, 2017. From left: Reg, Apurva, Annee, Hee-Jin, Shaopeng, Alana, Eric, Vivian, Hiro.

Accelerating Palladium Nanowire H2 Sensors Using Engineered Nanofiltration

Won-Tae Koo, Shaopeng Qiao, Alana F. Ogata, Gaurav Jha, Ji-Soo Jang, Vivian T. Chen, Il-Doo Kim* and Reginald M. Penner*,
ACS Nano 11 (2017) 9276.

Won-Tae Koo, a visiting student from KAIST in Korea, had the idea that the response and recovery speeds of H2 sensors could be accelerated by interposing a MOF nanofilter between the sensing element - an array of Pd NWs in this case - and the gaseous ambient. It worked, enabling the acceleration of sensing response in air by an amazing factor of 20. The nanofilter, which is highly permeable to H2 but impermeable other large gases, is a ZIF-8 MOF layer that is synthesized directly on top of the Pd NWs from methanolic solution. The acceleration of response and recovery are attributed to the exclusion of O2 from the surfaces of the Pd NW sensors.

A Nose for Hydrogen Gas: The Development of Fast, Sensitive H2 Sensors Using Electrodeposited Nanomaterials

Reginald M. Penner*,
Accounts of Chemical Research 50 (2017) 1902.

We've done a lot of work in the area of H2 sensors since Fred Favier, a visitor from CNRS Montpellier, made the first Pd nanowire devices here at UC Irvine back in 2001. I've tried to pull together a few of the highlights of our research over the last 15 years in this Account. As you can see from this page, we continue to have a lot of interest in this topic!

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© 2018, Reginald M. Penner