Dr. Eric Walter is a chemist with the Isotope and Chemical Analysis team in PNNL’s Environmental Molecular Sciences Division and the Environmental Molecular Sciences Laboratory (EMSL) user program. Walter is the contact for electron paramagnetic resonance (EPR). He assists EMSL users in applying both EPR and in situ nuclear magnetic resonance (NMR) to diverse fields, such as geochemistry, bio-catalysis, metalloproteins, and naturally occurring free-radicals.

Research Interest

  • In situ and operando magnetic resonance—Walter has developed numerous in situ sample cells for continuous flow, high pressure, and simultaneous electrochemistry for both EPR and NMR.
  • Walter has applied high performance, pulsed EPR spectroscopy to natural systems, such as soils and metalloproteins.


  • Postdoctoral Fellow, University of California, Santa Cruz, 2004 – 2009
  • PhD in Chemistry, Montana State University, 2004
  • BS in Chemistry, University of Delaware, 1996


Affiliations and Professional Service

  • American Chemical Society
  • International EPR Society


Awards and Recognitions

  • R&D100 Award for “PMAS Technology for NMR Spectroscopy” (2015)
  • Outstanding Performance Award, PNNL for “Catalytic N2 Reduction to Silylamines and Thermodynamics of N2 Binding at Square Planar Fe” published in Journal of the American Chemical Society. (2017)
  • Outstanding Publication Award, PNNL for “Inorganic tin aluminophosphate nanocomposite for reductive separation of pertechnetate” published in Environmental Science: Nano. (2016)


  • Walter, Eric; Sears, Jesse; Mehta, Hardeep; Hoyt, David. February 2020. “Snap-In Bushings and Process for High-Pressure and/or High Temperature Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy.” U.S. Patent 10,550,889.



  • Bowers G.M., E.D. Walter, S.D. Burton, K.C. Schwarz, D.W. Hoyt, and R.J. Kirkpatrick. 2020. "Probing Pore Size and Connectivity in Porous Silicas Using 13C MAS NMR Spectroscopy of Supercritical Methane." Journal of Physical Chemistry C 124, no. 21:11536-11543. PNNL-SA-153506. doi:10.1021/acs.jpcc.0c02718
  • Chatterjee S., M.S. Fujimoto, Y. Du, G.B. Hall, N. Lahiri, E.D. Walter, and L. Kovarik. 2020. "Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion." ACS Sensors 5, no. 3:674-685. PNNL-SA-143890. doi:10.1021/acssensors.9b01531
  • Cui, Y., Y. Wang, E. D. Walter, J. Szanyi, Y. Wang, and F. Gao. 2020. “Influences of Na+ co-Cation on the Structure and Performance of Cu/SSZ-13 Selective Catalytic Reduction Catalysts.” Catalysis Today 339: 233-240.
  • Huang X., Q. Zhao, R.P. Young, X. Zhang, E.D. Walter, Y. Chen, and E. Nakouzi, et al. 2020. "Photo-production of Reactive Oxygen Species and Degradation of Dissolved Organic Matter by Hematite Nanoplates Functionalized by Adsorbed Oxalate." Environmental Science: Nano 7, no. 8:2278-2292. PNNL-SA-148918. doi:10.1039/D0EN00365D
  • Peng B., K.G. Rappe, Y. Cui, F. Gao, J. Szanyi, M.J. Olszta, and E.D. Walter, et al. 2020. "Enhancement of high-temperature selectivity on Cu-SSZ-13 towards NH3-SCR reaction from highly dispersed ZrO2." Applied Catalysis B: Environmental 263. PNNL-SA-146190. doi:10.1016/j.apcatb.2019.118359
  • Sassi M., Z. Wang, E.D. Walter, X. Zhang, H. Zhang, X.S. Li, and A. Tuladhar, et al. 2020. "Surface Hydration and Hydroxyl Configurations of Gibbsite and Boehmite Nanoplates." Journal of Physical Chemistry C 124, no. 9:5275-5285. PNNL-SA-149815. doi:10.1021/acs.jpcc.0c00659
  • Walter E.D., K.C. Schwarz, S. Anil Kumar, Y. Chen, M. Sassi, Z. Wang, and K.M. Rosso. 2020. "Evolution of Radicals from the Photolysis of High Ionic Strength Alkaline Nitrite Solutions." Journal of Physical Chemistry A 124, no. 16:3019-3025. PNNL-SA-150363. doi:10.1021/acs.jpca.9b11438
  • Wang H., Y. Shao, H. Pan, X. Feng, Y. Chen, Y. Liu, and E.D. Walter, et al. 2020. "A lithium-sulfur battery with a solution-mediated pathway operating under lean electrolyte conditions." Nano Energy 76. PNNL-SA-143093. doi:10.1016/j.nanoen.2020.105041
  • Wang Z., E.D. Walter, M. Sassi, X. Zhang, H. Zhang, S. Li, and Y. Chen, et al. 2020. "The role of surface hydroxyls on the radiolysis of gibbsite and boehmite nanoplatelets." Journal of Hazardous Materials 398. PNNL-SA-150311. doi:10.1016/j.jhazmat.2020.122853
  • Zhang Y., Y. Peng, J. Li, K.J. Groden, J. Mcewen, E.D. Walter, and Y. Chen, et al. 2020. "Probing Active-Site Relocation in Cu/SSZ-13 SCR Catalysts during Hydrothermal Aging by in situ EPR Spectroscopy, Kinetic Studies, and DFT Calculations." ACS Catalysis 10, no. 16:9410-9419. PNNL-SA-152624. doi:10.1021/acscatal.0c01590


  • Bowers G.M., H.T. Schaef, Q. Miller, E.D. Walter, S.D. Burton, D.W. Hoyt, and J.A. Horner, et al. 2019. "13C Nuclear Magnetic Resonance Spectroscopy of Methane and Carbon Dioxide in a Natural Shale." ACS Earth and Space Chemistry 3, no. 3:324-328. PNNL-SA-140683. doi:10.1021/acsearthspacechem.8b00214
  • Bowers G.M., J.S. Loring, E.D. Walter, S.D. Burton, M.E. Bowden, D.W. Hoyt, and B.W. Arey, et al. 2019. "Influence of Smectite Structure and Hydration on Supercritical Methane Binding and Dynamics in Smectite Pores." Journal of Physical Chemistry C 123, no. 48:29231-29244. PNNL-SA-146425. doi:10.1021/acs.jpcc.9b08875
  • Chacon S.S., P.N. Reardon, C.J. Burgess, S.O. Purvine, R.K. Chu, T.R. Clauss, and E.D. Walter, et al. 2019. "Mineral Surfaces as Agents of Environmental Proteolysis: Mechanisms and Controls." Environmental Science & Technology 53, no. 6:3018-3026. PNNL-SA-141783. doi:10.1021/acs.est.8b05583
  • Chamas A., L. Qi, H.S. Mehta, J.A. Sears, S.L. Scott, E.D. Walter, and D.W. Hoyt. 2019. "High Temperature/Pressure MAS-NMR for the Study of Dynamic Processes in Mixed Phase Systems." Magnetic Resonance Imaging 56. PNNL-SA-138048. doi:10.1016/j.mri.2018.09.026
  • Cui W., X. Zhang, C.I. Pearce, Y. Chen, S. Zhang, W. Liu, and M.H. Engelhard, et al. 2019. "Cr(III) adsorption by cluster formation on boehmite nanoplates in highly alkaline solution." Environmental Science & Technology 53, no. 18:11043-11055. PNNL-SA-143650. doi:10.1021/acs.est.9b02693
  • Cui Y., Y. Wang, D. Mei, E.D. Walter, N.M. Washton, J.D. Holladay, and Y. Wang, et al. 2019. "Revisiting effects of alkali metal and alkaline earth co-cation additives to Cu/SSZ-13 selective catalytic reduction catalysts." Journal of Catalysis 378. PNNL-SA-141699. doi:10.1016/j.jcat.2019.08.028
  • Earla A., E.D. Walter, and R. Braslau. 2019. "Synthesis and Spin Trapping Properties of Polystyrene Supported Trifluoromethylated Cyclic Nitrones." Free Radical Research 53, no. 11-12:1084-1100. PNNL-SA-147124. doi:10.1080/10715762.2019.1683171
  • Jaegers N.R., J. Lai, Y. He, E.D. Walter, D.A. Dixon, M. Vasiliu, and Y. Chen, et al. 2019. "Mechanism by which Tungsten Oxide Promotes the Activity of Supported V2O5/TiO2 Catalysts for NOX Abatement: Structural Effects Revealed by 51V MAS NMR Spectroscopy." Angewandte Chemie International Edition 58, no. 36:12609-12616. PNNL-SA-141251. doi:10.1002/anie.201904503
  • Mehta H.S., Y. Chen, J.A. Sears, E.D. Walter, M. Campos, J. Kothandaraman, and D.J. Heldebrant, et al. 2019. "A Novel High-Temperature MAS Probe with Optimized Temperature Gradient across Sample Rotor for In-situ Monitoring of High-Temperature High-Pressure Chemical Reactions." Solid State Nuclear Magnetic Resonance 102. PNNL-SA-143153. doi:10.1016/j.ssnmr.2019.06.003
  • Miller Q., D.A. Dixon, S.D. Burton, E.D. Walter, D.W. Hoyt, A.S. Mcneill, and J. Moon, et al. 2019. "Surface-Catalyzed Oxygen Exchange during Mineral Carbonation in Nanoscale Water Films." Journal of Physical Chemistry C 123, no. 20:12871-12885. PNNL-SA-141756. doi:10.1021/acs.jpcc.9b02215
  • Prokopchuk D.E., G.M. Chambers, E.D. Walter, M.T. Mock, and R.M. Bullock. 2019. "H2 Binding, Splitting, and Net Hydrogen Atom Transfer at a Paramagnetic Iron Complex." Journal of the American Chemical Society 141, no. 5:1871-1876. PNNL-SA-139955. doi:10.1021/jacs.8b12823
  • Qi L., A. Chamas, Z.R. Jones, E.D. Walter, D.W. Hoyt, N.M. Washton, and S.L. Scott. 2019. "Unraveling the Dynamic Network in the Reactions of an Alkyl Aryl Ether Catalyzed by Ni/y-Al2O3 in 2-Propanol." Journal of the American Chemical Society 141, no. 43:17370-17381. PNNL-SA-148402. doi:10.1021/jacs.9b09071
  • Stavila V., M. Foster, J.W. Brown, R.W. Davis, J. Edgington, A.I. Benin, and R.A. Zarkesh, et al. 2019. "IRMOF-74(n)-Mg: a novel catalyst series for hydrogen activation and hydrogenolysis of C-O bonds." Chemical Science 10, no. 42:9880-9892. PNNL-SA-147308. doi:10.1039/C9SC01018A
  • Wang A., Y. Chen, E.D. Walter, N.M. Washton, D. Mei, T. Varga, and Y. Wang, et al. 2019. "Unraveling the mysterious failure of Cu/SAPO-34 selective catalytic reduction catalysts." Nature Communications 10, no. 1:Article No. 1137. PNNL-SA-138654. doi:10.1038/s41467-019-09021-3
  • Wang A., Y. Wang, E.D. Walter, N.M. Washton, Y. Guo, G. Lu, and C. Peden, et al. 2019. "NH3-SCR on Cu, Fe and Cu+Fe exchanged Beta and SSZ-13 catalysts: hydrothermal aging and propylene poisoning effects." Catalysis Today 320. PNNL-SA-128427. doi:10.1016/j.cattod.2017.09.061


  • Kothandaraman J., R.A. Dagle, V. Dagle, S.D. Davidson, E.D. Walter, S.D. Burton, and D.W. Hoyt, et al. 2018. "Condensed-Phase Low Temperature Heterogeneous Hydrogenation of CO2 to Methanol." Catalysis Science & Technology 8, no. 19:5098-5103. PNNL-SA-133245. doi:10.1039/C8CY00997J
  • Reardon P.N., E.D. Walter, C.L. Marean-Reardon, C.W. Lawrence, M.W. Kleber, and N.M. Washton. 2018. "Carbohydrates Protect Protein Against Abiotic Fragmentation By Soil Minerals." Scientific Reports 8. PNNL-SA-132243. doi:10.1038/s41598-017-19119-7
  • Walter E.D., L. Qi, A. Chamas, H.S. Mehta, J.A. Sears, S.L. Scott, and D.W. Hoyt. 2018. "Operando MAS NMR Reaction Studies at High Temperatures and Pressures." Journal of Physical Chemistry C 122, no. 15:8209-8215. PNNL-SA-130852. doi:10.1021/acs.jpcc.7b11442
  • Wang A., Y. Wang, E.D. Walter, R.K. Kukkadapu, Y. Guo, G. Lu, and R.S. Weber, et al. 2018. "Catalytic N2O decomposition and reduction by NH3 over Fe/Beta and Fe/SSZ-13 catalysts." Journal of Catalysis 358. PNNL-SA-128426. doi:10.1016/j.jcat.2017.12.011
  • Weaver J.L., C.Z. Soderquist, N.M. Washton, P.L. Gassman, E.D. Walter, M.E. Bowden, and W.W. Lukens, et al. 2018. "Challenges and Solutions for Handling and Characterizing Alkali-Tc-Oxide Salts." MRS Advances 3, no. 21:1191-1200. PNNL-SA-130916. doi:10.1557/adv.2018.165


  • Bowers G.M., H.T. Schaef, J.S. Loring, D.W. Hoyt, S.D. Burton, E.D. Walter, and R.J. Kirkpatrick. 2017. "Role of Cations in CO2 Adsorption, Dynamics, and Hydration in Smectite Clays Under in situ Supercritical CO2 Conditions." Journal of Physical Chemistry C 121, no. 1:577-592. PNNL-SA-122523. doi:10.1021/acs.jpcc.6b11542
  • Chatterjee S., A. Andersen, Y. Du, M.H. Engelhard, G.B. Hall, T.G. Levitskaia, and W.W. Lukens, et al. 2017. Characterization of Non-pertechnetate Species Relevant to the Hanford Tank Waste. PNNL-26265. Richland, WA: Pacific Northwest National Laboratory. Characterization of Non-pertechnetate Species Relevant to the Hanford Tank Waste
  • Duan W., J. Huang, J.A. Kowalski, I.A. Shkrob, V. Murugesan, E.D. Walter, and B. Pan, et al. 2017. "Wine-Dark Sea in An Organic Flow Battery: Storing Negative Charge in 2,1,3-Benzothiadiazole Radicals Leads to Improved Cyclability." ACS Energy Letters 2, no. 5:1156-1161. PNNL-SA-120607. doi:10.1021/acsenergylett.7b00261
  • Jaegers N.R., C. Wan, M.Y. Hu, M. Vasiliu, D.A. Dixon, E.D. Walter, and I. Wachs, et al. 2017. "Investigation of silica-supported vanadium oxide catalysts by high-field 51V Magic Angle Spinning NMR." Journal of Physical Chemistry C 121, no. 11:6246-6254. PNNL-SA-124184. doi:10.1021/acs.jpcc.7b01658
  • Kim K., T. Dutta, E.D. Walter, N.G. Isern, J.R. Cort, B.A. Simmons, and S. Singh. 2017. "Chemoselective Methylation of Phenolic Hydroxyl Group Prevents Quinone Methide Formation and Repolymerization during Lignin Depolymerization." ACS Sustainable Chemistry & Engineering 5, no. 5:3913-3919. PNNL-SA-122183. doi:10.1021/acssuschemeng.6b03102
  • Liu B., W. Xu, J. Zheng, P. Yan, E.D. Walter, N.G. Isern, and M.E. Bowden, et al. 2017. "Temperature dependence of the oxygen reduction mechanism in nonaqueous Li-O2 batteries." ACS Energy Letters 2. PNNL-SA-126517. doi:10.1021/acsenergylett.7b00845
  • Prodinger S., M.A. Derewinski, Y. Wang, N.M. Washton, E.D. Walter, J. Szanyi, and F. Gao, et al. 2017. "Sub-micron Cu/SSZ-13: synthesis and application as selective catalytic reduction (SCR) catalysts." Applied Catalysis. B, Environmental 201. PNNL-SA-117975. doi:10.1016/j.apcatb.2016.08.053
  • Prokopchuk D.E., E.S. Wiedner, E.D. Walter, C.V. Popescu, N.A. Piro, W.S. Kassel, and R.M. Bullock, et al. 2017. "Catalytic N2 Reduction to Silylamines and Thermodynamics of N2 Binding at Square Planar Fe." Journal of the American Chemical Society 139, no. 27:9291-9301. PNNL-SA-125864. doi:10.1021/jacs.7b04552
  • Qi L., R. Alamillo, W.A. Elliott, A. Andersen, D.W. Hoyt, E.D. Walter, and K. Han, et al. 2017. "Operando solid-state NMR observations of solvent-mediated adsorption-reaction of carbohydrates in zeolites." ACS Catalysis 7, no. 5:3489-3500. PNNL-SA-119548. doi:10.1021/acscatal.7b01045
  • Song J., Y. Wang, E.D. Walter, N.M. Washton, D. Mei, L. Kovarik, and M.H. Engelhard, et al. 2017. "Towards rational design of Cu/SSZ-13 selective catalytic reduction catalysts: Implications from atomic-level understanding of hydrothermal stability." ACS Catalysis 7, no. 12:8214-8227. PNNL-SA-128659. doi:10.1021/acscatal.7b03020
  • Weaver J.L., C.Z. Soderquist, P.L. Gassman, E.D. Walter, W.W. Lukens, and J.S. McCloy. 2017. "Synthesis and Characterization of 5- and 6- Coordinated Alkali Pertechnetates." MRS Advances 2, no. 10:525-542. PNNL-SA-123560. doi:10.1557/adv.2017.18


  • Gao F., Y. Zheng, R.K. Kukkadapu, Y. Wang, E.D. Walter, B. Schwenzer, and J. Szanyi, et al. 2016. "Iron loading effects in Fe/SSZ-13 NH3-SCR catalysts: nature of the Fe-ions and structure-function relationships." ACS Catalysis 6, no. 5:2939-2954. PNNL-SA-113591. doi:10.1021/acscatal.6b00647
  • Huang Q., E.D. Walter, L. Cosimbescu, D. Choi, and J.P. Lemmon. 2016. "In situ electrochemical-electron spin resonance investigations of multi-electron redox reaction for organic radical cathodes." Journal of Power Sources 306. PNNL-SA-107032. doi:10.1016/j.jpowsour.2015.11.080
  • Levitskaia T.G., S. Chatterjee, N. Pence, J. Romero, T. Varga, M.H. Engelhard, and Y. Du, et al. 2016. "Inorganic Tin Aluminophosphate Nanocomposite for Reductive Separation of Pertechnetate." Environmental Science: Nano 3, no. 2:1003-1013. PNNL-SA-116229. doi:10.1039/C6EN00130K
  • Li Y., Y. Xie, Z. Wang, N. Zang, F. Carniato, Y. Huang, and C. Andolina, et al. 2016. "Structure and Function of Iron-Loaded Synthetic Melanin." ACS Nano 10, no. 11:10186-10194. PNNL-SA-120425. doi:10.1021/acsnano.6b05502
  • Reardon P.N., S.S. Chacon, E.D. Walter, M.E. Bowden, N.M. Washton, and M.W. Kleber. 2016. "Abiotic protein fragmentation by manganese oxide: implications for a mechanism to supply soil biota with oligopeptides." Environmental Science & Technology 50, no. 7:3486-3493. PNNL-SA-108407. doi:10.1021/acs.est.5b04622