Valerie Niemann

All Publications

• Calcium-mediated nitrogen reduction for electrochemical ammonia synthesis. Nature materials Fu, X., Niemann, V. A., Zhou, Y., Li, S., Zhang, K., Pedersen, J. B., Saccoccio, M., Andersen, S. Z., Enemark-Rasmussen, K., Benedek, P., Xu, A., Deissler, N. H., Mygind, J. B., Nielander, A. C., Kibsgaard, J., Vesborg, P. C., Norskov, J. K., Jaramillo, T. F., Chorkendorff, I. 2023

  Abstract

  Ammonia (NH3) is a key commodity chemical for the agricultural, textile and pharmaceutical industries, but its production via the Haber-Bosch process is carbon-intensive and centralized. Alternatively, an electrochemical method could enable decentralized, ambient NH3 production that can be paired with renewable energy. The first verified electrochemical method for NH3 synthesis was a process mediated by lithium (Li) in organic electrolytes. So far, however, elements other than Li remain unexplored in this process for potential benefits in efficiency, reaction rates, device design, abundance and stability. In our demonstration of a Li-free system, we found that calcium can mediate the reduction of nitrogen for NH3 synthesis. We verified the calcium-mediated process using a rigorous protocol and achieved an NH3 Faradaic efficiency of 40±2% using calcium tetrakis(hexafluoroisopropyloxy)borate (Ca[B(hfip)4]2) as the electrolyte. Our results offer the possibility of using abundant materials for the electrochemical production of NH3, a critical chemical precursor and promising energy vector.

  View details for DOI 10.1038/s41563-023-01702-1

  View details for PubMedID 37884670

• Quantifying Influence of the Solid-Electrolyte Interphase in Ammonia Electrosynthesis ACS ENERGY LETTERS Mcshane, E. J., Niemann, V. A., Benedek, P., Fu, X., Nielander, A. C., Chorkendorff, I., Jaramillo, T. F., Cargnello, M. 2023

  View details for DOI 10.1021/acsenergylett.3c01534

  View details for Web of Science ID 001062617200001

• Development of a versatile electrochemical cell for in situ grazing-incidence X-ray diffraction during non-aqueous electrochemical nitrogen reduction. Journal of synchrotron radiation Blair, S. J., Nielander, A. C., Stone, K. H., Kreider, M. E., Niemann, V. A., Benedek, P., McShane, E. J., Gallo, A., Jaramillo, T. F. 2023

  Abstract

  In situ techniques are essential to understanding the behavior of electrocatalysts under operating conditions. When employed, in situ synchrotron grazing-incidence X-ray diffraction (GI-XRD) can provide time-resolved structural information of materials formed at the electrode surface. In situ cells, however, often require epoxy resins to secure electrodes, do not enable electrolyte flow, or exhibit limited chemical compatibility, hindering the study of non-aqueous electrochemical systems. Here, a versatile electrochemical cell for air-free in situ synchrotron GI-XRD during non-aqueous Li-mediated electrochemical N2 reduction (Li-N2R) has been designed. This cell not only fulfills the stringent material requirements necessary to study this system but is also readily extendable to other electrochemical systems. Under conditions relevant to non-aqueous Li-N2R, the formation of Li metal, LiOH and Li2O as well as a peak consistent with the alpha-phase of Li3N was observed, thus demonstrating the functionality of this cell toward developing a mechanistic understanding of complicated electrochemical systems.

  View details for DOI 10.1107/S1600577523006331

  View details for PubMedID 37594864

• Combined, time-resolved, in situ neutron reflectometry and X-ray diffraction analysis of dynamic SEI formation during electrochemical N-2 reduction ENERGY & ENVIRONMENTAL SCIENCE Blair, S. J., Doucet, M., Niemann, V. A., Stone, K. H., Kreider, M. E., Browning, J. F., Halbert, C. E., Wang, H., Benedek, P., McShane, E. J., Nielander, A. C., Gallo, A., Jaramillo, T. F. 2023

  View details for DOI 10.1039/d2ee03694k

  View details for Web of Science ID 001018487700001

• X-ray Absorption Spectroscopy Reveals Mechanisms of Calcium and Silicon Fouling on Reverse Osmosis Membranes Used in Wastewater Reclamation ACS ES&T WATER Niemann, V. A., Huck, M., Steinrueck, H., Toney, M. F., Tarpeh, W. A., Bone, S. E. 2023

  View details for DOI 10.1021/acsestwater.3c00144

  View details for Web of Science ID 001011366200001

• Co-designing Electrocatalytic Systems with Separations To Improve the Sustainability of Reactive Nitrogen Management ACS CATALYSIS Niemann, V. A., Benedek, P., Guo, J., Xu, Y., Blair, S. J., Corson, E. R., Nielander, A. C., Jaramillo, T. F., Tarpeh, W. A. 2023; 13 (9): 6268-6279

  View details for DOI 10.1021/acscatal.3c00933

  View details for Web of Science ID 000983745600001

• Hydrogen production with seawater-resilient bipolar membrane electrolyzers JOULE Marin, D. H., Perryman, J. T., Hubert, M. A., Lindquist, G. A., Chen, L., Aleman, A. M., Kamat, G. A., Niemann, V. A., Stevens, M., Regmi, Y. N., Boettcher, S. W., Nielander, A. C., Jaramillo, T. F. 2023; 7 (4): 765-781

  View details for DOI 10.1016/j.joule.2023.03.005

  View details for Web of Science ID 000988108000001

• A Versatile Li0.5FePO4 Reference Electrode for Nonaqueous Electrochemical Conversion Technologies ACS ENERGY LETTERS McShane, E. J., Benedek, P., Niemann, V. A., Blair, S. J., Kamat, G. A., Nielander, A. C., Jaramillo, T. F., Cargnello, M. 2022: 230-235

  View details for DOI 10.1021/acsenergylett.2c02190

  View details for Web of Science ID 000891330700001