Breaking adsorption-energy scaling limitations of electrocatalytic nitrate reduction on intermetallic CuPd nanocubes by machine-learned insights

Abstract

The electrochemical nitrate reduction reaction (NO3RR) to ammonia is an essential step toward restoring the globally disrupted nitrogen cycle. In search of highly efficient electrocatalysts, tailoring catalytic sites with ligand and strain effects in random alloys is a common approach but remains limited due to the ubiquitous energy-scaling relations. With interpretable machine learning, we unravel a mechanism of breaking adsorption-energy scaling relations through the site-specific Pauli repulsion interactions of the metal d-states with adsorbate frontier orbitals. The non-scaling behavior can be realized on (100)-type sites of ordered B2 intermetallics, in which the orbital overlap between the hollow *N and subsurface metal atoms is significant while the bridge-bidentate *NO3 is not directly affected. Among those intermetallics predicted, we synthesize monodisperse ordered B2 CuPd nanocubes that demonstrate high performance for NO3RR to ammonia with a Faradaic efficiency of 92.5% at −0.5 VRHE and a yield rate of 6.25 mol h−1 g−1 at −0.6 VRHE. This study provides machine-learned design rules besides the d-band center metrics, paving the path toward data-driven discovery of catalytic materials beyond linear scaling limitations.

FeS2@TiO2 nanobelt array enabled high-efficiency electrocatalytic nitrate reduction to ammonia

“…From both economic and environmental viewpoints, electroreduction NO 3 − to NH 3 is a favorable sustainable route in the N cycle for large-scale ambient NH 3 production and has significant effects on mitigating NO 3 − pollution, realizing the alteration of “waste-to-wealth”. 36–42 The related electrochemical equation is shown in eqn (1), where the thermodynamic potential is 0.69 V versus reversible hydrogen electrode (RHE).NO 3 − + 6H 2 O + 8e − → NH 3 + 9OH − …”

Study on the formation mechanism of asymmetric growth hillocks on pyramidal faces of KDP crystals

“…The adsorption energy of the facing steps is expressed in eqn (3), 33 E ad = [ E (a+b) − E a − nE b ]/ n where E ad is the adsorption energy of a single KH 2 PO 4 molecule on the facing steps, E (a+b) is the system energy after adsorption, E a is the system energy before adsorption, E b is the energy of a single KH 2 PO 4 molecule in the bulk structure, and n is the amount of KH 2 PO 4 molecules contained in the atomic structure of the facing steps. The calculated values of the parameters in the above formula are listed in Table 3.…”

Intermetallic Nanoarchitectures for Efficient Electrocatalysis

“…As an another example, Zhu and co-workers designed intermetallic CuPd nanocubes catalyzing nitrate reduction reaction (NO 3 RR) . For the NO 3 RR, Cu (100) surface is a highly selective catalytic surface toward NH 3 formation as shown by the previous single crystal-based studies.…”

“…The wet-chemical approach, a powerful method for preparing shape-controlled nanocrystals, enables the bottom-up synthesis of facetcontrolled intermetallic nanocrystals. [6][7][8][9][10]18,19 The successful preparation of the intermetallic nanocrystals with well-defined shapes rests on the judicious selection of structure directing agents. In addition, the reaction rate should be controlled to induce a simultaneous occurrence of particle growth in specific directions and the atomic ordering.…”

“…Thermally stable SiO 2 , MgO, and carbon-shell have been found suitable as protective layers. More importantly, the intermetallic nanoarchitectures, which refer to intermetallic catalysts with uniform size and controlled shape in nanoscale, have demonstrated unprecedented enhancement in catalytic performances. ,− Nanoarchitectures, including facet-controlled nanocrystals and multidimensional nanostructures, often expose well-defined crystallographic planes or highly strained surfaces from curved planes, undercoordinated defects, and grain boundaries. These structural features of intermetallic nanoarchitectures engender different binding strengths of reaction intermediates from typical intermetallic NPs, boosting catalytic performance.…”