Scalable Manufacturing of Metal Oxide Nano-Array integrated Monoliths (Supported by NSF SNM Award No. CBET-1344792)

Sibo Wang,1 Xingxu Lu,1 Yunchao Wu,2 Wenxiang Tang,1 Mingwan Zhang,1 Sheng-Yu Chen,3 Yanbing Guo,1 Son Hoang,1

Andrew J. Binder,5 Eleni A. Kyriakidou,5 Shoucheng Du,1 Todd J. Toops,5 Zhuyin Ren,2 Tianfeng Lu,2 Steven L. Suib,3,4 and Pu-Xian Gao1,4,* Departments of 1Materials Science and Engineering, 2Mechanical Engineering, and 3Chemistry, & 4Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA;

5National Transportation Research Center, Oak Ridge National Laboratory, Oak Ridge, TN 37932, USA; * E-mail: puxian.gao@uconn.edu

Introduction Scalable integration of elemental nanostructures such

as nanorods and nanowires into practically functional

nano-ensembles, devices, or systems represents a

critical step toward accelerating nanotechnology

transfer and commercialization [1]. Here we present the

latest progress of scalable manufacturing of a unique

class of 3-D nanostructure array (nano-array) integrated

monolithic devices for energy and environmental

applications.

Figure 1. In-situ grown nanostructure arrays on 3-D channeled

honeycomb monoliths as a new class of catalytic converters for

emission control in both mobile and stationary sources.[1-11]

Method

Figure 2. An example experimental setup of microwave-assisted continuous flow synthesis (CFS).

Results and discussion

A low-temperature microwave-assisted hydrothermal based continuous flow synthesis was successfully

conducted to integrate uniformly distributed large-scale metal oxide nanostruture arrays (nano-arrays) with

full-size commercial 3D cordierite honeycomb substrates. Compared to traditional batch process, the CFS

possess allows significantly enhanced growth rate, distribution uniformity across the channel length, and

improved precursor utilization efficiency. With the assistance of microwave and sophisticate setup design, the

novel continuous flow hydrothermal synthesis holds great promise towards industrial-relevant scalable

manufacturing of 3-D nano-array based monolithic devices for energy and environmental applications.

The authors are grateful for the financial

support from the NSF Scalable

Nanomanufacturing (SNM) program

through award No. CBET-1344792, the

DoE Vehicle Technologies Incubator

Program through award No. DE-

EE0006854, and the University of

Connecticut Spark Program. Industrial

collaboration from Corning, Umicore and

3D Array Technology are appreciated.

1. S.B. Wang, Z. Ren, Y.B. Guo, P.X. Gao, CrystEngComm, 2016, 18, 2980 - 2993.

2. Y. Guo, Z. Ren, P.X. Gao et al., Nano Energy 2013, 2, 873-881.

3. Z. Ren, Y.B. Guo, P.X. Gao, Catalysis Today, 2015, 441-453.

4. W. Tang, P.X. Gao, MRS Communications, 2016, DOI:10.1557/mrc.2016.52.

5. S.B. Wang, Y.C. Wu, Z.Y. Ren, T. Lu, S.L. Suib, P.X. Gao et al., 2016, submitted.

6. Z. Ren, R. Ramprasad, S.L. Suib, P.X. Gao et al., Angew. Chem., Int. Ed. 2014, 53, 7223–7227.

7. Z. Ren, Z. Wu, S.L. Suib, P.X. Gao et al., Appl. Catal. B, 2016, 180, 150–160.

8. S.B. Wang, Z. Ren, W.Q. Song, Y.B. Guo, S.L. Suib, P.X. Gao, Catalysis Today, 2015, 549-555.

9. S.Y. Chen, P.X. Gao, S. Suib, et al., ACS Materials & Interfaces, 2016, 8 (12), 7834–7842.

10. S.C. Du, P.X. Gao et al., Emission Control Sci. Tech. 2016, DOI: 10.1007/s40825-016-0054-y.

11. S. Hoang, and P.X. Gao, Adv. Energy Mater. 2016, 1600683 (1-29).

.

Conclusions References Acknowledgements

Figure 7. Nano-array integrated diesel oxidation catalysts of Ø2″~7.5″×

L3″~6″ being tested at Umicore Autocat USA for high dynamic syn-gas

bench and engine dyno performance.

Microwave-assisted CFS processing: full-size TiO2 (bottom)

and ZnO (right) nano-array integrated cordierite monoliths

Low temperature; Microwave acceleration;

Large scale; High throughput; Efficient precursor utilization

ppm (C1-basis) % of THC

C2H4 1667 ppm 55.6%

C2H6 1000 ppm 33.3%

C2H8 333 ppm 11.1%

The low Pt-group metal loaded metal oxide nano-array based catalytic converter performance approaches the T90 = 150°C goal set by the automotive industry for total oxidation of CO and most hydrocarbons. However, propane oxidation still poses a challenge.

Filter (Cooling)

Cooling Water

Microwave Oven

Pump

Pump

Solution

Figure 5. (a) (b) cross-sectional

view and (c) top view of

monolithically integrated ZnO

nano-array on commercial

honeycomb substrate (d) via CFS;

(e) X-ray diffraction patterns of

bare cordierite substrate and ZnO

nanorod array integrated

cordierite honeycomb substrate.

Figure 6. (a) Geometric parameters

employed in fluid dynamic

simulation; (b) computational flow

velocity of solution at the entrance

of substrate channels versus

channel position in CFS; (c) Zn2+

concentration variation as a

function of reaction time in CFS and

batch process and the inset of

solution reservoir; (d) average

length of ZnO nano-array obtained

from CFS (30 ml/min·cm2) and

batch process vs growth time;

Figure 8. Catalytic diesel oxidation

performance of metal oxide/PGM nano-

array based catalytic converter under

simulated low temperature combustion of

diesel (LTC-D) exhaust conditions.

Figure 3.

SEM analysis:

Uniform distribution of TiO2 nano-arrays on full-size honeycomb.

Figure 4. TEM analysis: well dispersed 1-2 nm Pt on TiO2 nano-arrays.