TY  - JOUR
A1  - Qin, Qing
A1  - Oschatz, Martin
T1  - Overcoming chemical inertness under ambient conditions
BT  - a critical view on recent developments in Ammonia synthesis via electrochemical N-2 reduction by asking five questions
JF  - ChemElectroChem
N2  - Ammonia (NH3) synthesis by the electrochemical N-2 reduction reaction (NRR) is increasingly studied and proposed as an alternative process to overcome the disadvantages of Haber-Bosch synthesis by a more energy-efficient, carbon-free, delocalized, and sustainable process. An ever-increasing number of scientists are working on the improvement of the faradaic efficiency (FE) and NH3 production rate by developing novel catalysts, electrolyte concepts, and/or by contributing theoretical studies. The present Minireview provides a critical view on the interplay of different crucial aspects in NRR from the electrolyte, over the mechanism of catalytic activation of N-2, to the full electrochemical cell. Five critical questions are asked, discussed, and answered, each coupled with a summary of recent developments in the respective field. This article is not supposed to be a complete summary of recent research about NRR but provides a rather critical personal view on the field. It is the major aim to give an overview over crucial influences on different length scales to shine light on the sweet spots into which room for revolutionary instead of incremental improvements may exist.
KW  - N-2 reduction
KW  - ammonia synthesis
KW  - catalysis
KW  - catalysts
KW  - electrolytes
Y1  - 2022
U6  - https://doi.org/10.1002/celc.201901970
SN  - 2196-0216
VL  - 7
IS  - 4
SP  - 878
EP  - 889
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Qin, Qing
A1  - Zhao, Yun
A1  - Schmallegger, Max
A1  - Heil, Tobias
A1  - Schmidt, Johannes
A1  - Walczak, Ralf
A1  - Gescheidt-Demner, Georg
A1  - Jiao, Haijun
A1  - Oschatz, Martin
T1  - Enhanced Electrocatalytic N-2 Reduction via Partial Anion Substitution in Titanium Oxide-Carbon Composites
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - The electrochemical conversion of N-2 at ambient conditions using renewably generated electricity is an attractive approach for sustainable ammonia (NH3) production. Considering the chemical inertness of N-2, rational design of efficient and stable catalysts is required. Therefore, in this work, it is demonstrated that a C-doped TiO2/C (C-TixOy/C) material derived from the metal-organic framework (MOF) MIL-125(Ti) can achieve a high Faradaic efficiency (FE) of 17.8 %, which even surpasses most of the established noble metal-based catalysts. On the basis of the experimental results and theoretical calculations, the remarkable properties of the catalysts can be attributed to the doping of carbon atoms into oxygen vacancies (OVs) and the formation of Ti-C bonds in C-TixOy. This binding motive is found to be energetically more favorable for N-2 activation compared to the non-substituted OVs in TiO2. This work elucidates that electrochemical N-2 reduction reaction (NRR) performance can be largely improved by creating catalytically active centers through rational substitution of anions into metal oxides.
KW  - ammonia synthesis
KW  - anion substitution
KW  - MOF-derived catalysts
KW  - N-2 fixation
KW  - non-noble metal catalysts
Y1  - 2019
U6  - https://doi.org/10.1002/anie.201906056
SN  - 1433-7851
SN  - 1521-3773
VL  - 58
IS  - 37
SP  - 13101
EP  - 13106
PB  - Wiley-VCH
CY  - Weinheim
ER  -