Screening of Transition Metal Oxides for Electrocatalytic Nitrate
Reduction to Ammonia at High Currents
Abstract
Electrochemical nitrate reduction reaction (NtrRR) towards ammonia, as
an emerging and appealing technology alternative to the energy-intensive
Haber-Bosch process and inefficient nitrogen reduction reaction, has
recently aroused wide concern and research. However, the current
research of the NtrRR towards ammonia lacks the overall performance
comparison of various electrocatalysts. Given this, we here make a
comparison of 12 common transition metal oxide catalysts for the NtrRR
under a high cathodic current density of 0.25 A cm-2, wherein Co3O4
catalyst displays the best NtrRR selectivity towards ammonia with a
highest Faradaic efficiency (85.15%) and a moderate NtrRR activity.
Other external factors, such as nitrate concentrations in the
electrolyte and applied potential ranges, have also been specifically
investigated for the NtrRR. This work can provide constructive guidance
to engineer the NtrRR electrocatalysts with higher activity, selectivity
and stability in the future.