open access publication

Preprint, 2024

In situ neutron reflectometry reveals the interfacial microenvironment driving electrochemical ammonia synthesis

ChemRxiv, ISSN 2573-2293, 10.26434/chemrxiv-2024-8g61h

Contributors

Niemann, Valerie Anne 0000-0002-9565-022X [1] [2] Doucet, Mathieu 0000-0002-5560-6478 [3] Benedek, Peter [1] [2] Deissler, Niklas Henrik 0000-0001-9117-5030 [4] Mygind, Jon Bjarke Valbaek 0000-0003-2032-4152 [4] Lee, Sang-Won [1] [2] Chorkendorff, I B 0000-0003-2738-0325 [4] Nielander, Adam C 0000-0002-3639-2427 [1] Tarpeh, William Abraham 0000-0002-2950-526X [1] [2] Jaramillo, Thomas Francisco 0000-0001-9900-0622 [1] [2]

Affiliations

  1. [1] SLAC National Accelerator Laboratory
    2. [NORA names: United States; America, North; OECD];
  2. [2] Stanford University
    3. [NORA names: United States; America, North; OECD];
  3. [3] Oak Ridge National Laboratory
    4. [NORA names: United States; America, North; OECD];
  4. [4] Technical University of Denmark
    5. [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD]

Abstract

Electrified interfaces are critical to the performance of energy systems and often demonstrate substantial complexity under operating conditions. Nanoscale understanding of the interfacial microenvironment, i.e., the solid electrolyte interphase (SEI), in lithium-mediated nitrogen reduction (Li-N2R) is key for realizing efficient ammonia production. Using in situ neutron reflectometry, we found the Li-N2R SEI comprises a thick, diffuse outer layer and a thin, compact inner layer at low current cycling. Increasing current density resulted in a thinner outer layer with a thicker inner layer; sustained current led to LiH formation. Neutron absorption indicated boron uptake in the SEI. Time-resolved tracking of SEI growth with isotope contrasting revealed the proton donor modifies the inner layer, and the solvent modifies the outer layer. Li dendritic growth was observed in the absence of a proton donor. Our results inform Li-based systems and reaction microenvironments, and these methods can be applied broadly to interfacial energy technologies.

Keywords

Li dendrite growth, Li-based systems, LiH, LiH formation, SEI growth, absence, absorption, ammonia production, ammonia synthesis, boron, boron uptake, compact inner layer, complex, conditions, contrast, current cycling, current density, cycle, dendrite growth, density, donor, efficient ammonia production, electrified interfaces, electrochemical ammonia synthesis, electrolyte interphase, energy systems, energy technologies, formation, growth, i., in situ neutron reflectometry, increasing current density, inner layer, interface, interfacial microenvironment, interphase, isotopes, isotopic contrast, layer, method, microenvironment, nanoscale, nanoscale understanding, neutron, neutron absorption, neutron reflectometry, nitrogen reduction, operating conditions, operation, outer layer, performance, performance of energy systems, production, proton, proton donor, reaction, reaction microenvironment, reduction, reflectometry, solid electrolyte interphase, solvent, synthesis, system, technology, time-resolved tracking, understanding, uptake

Funders

  • The Velux Foundations
  • Camille and Henry Dreyfus Foundation

Data Provider: Digital Science

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