Metal‐to‐Oxide Molar Volume Ratio: The Overlooked Barrier to Solid‐State Electroreduction and a “Green” Bypass through Recyclable NH₄HCO₃

Abstract

Beating the barrier: The metal-to-oxide molar volume ratio Vm/Vo determines whether electroreduction of a metal oxide forms a porous metal shell that allows reduction to proceed (Vm/Vo≪1), or nonporous one that causes it to cease (Vm/Vo≥1; see picture). In the case of TiO2 (Vm/Vo≈1), this barrier to reduction to Ti can be circumvented by recyclable use of NH4HCO3 as a fugitive porogenic agent. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.