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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Modulation of the coordination environment enhances the electrocatalytic efficiency of Mo single atoms toward water splitting

Here, enhancing the catalytic efficiency through engineering active site environments is expected to work pronouncedly for single atom catalysts (SACs) because of intense atomic scale interactions involved between SAs and their coordination environments. Taking Mo SACs for catalyzation of the hydrogen evolution reaction (HER) as an example, three SACs of different coordination environments, namely Mo-O 2 N 2 , Mo-O 2 N 1 C 1 , and Mo-O 2 C 2 , were successfully created for demonstration. The HER performances are in an increasing order of Mo-O 2 N 2 , Mo-O 2 N 1 C 1 , and Mo-O 2 C 2 , exhibiting η 10 of 98, 71, and 61 mV, η 500 of 340, 248, and 200 mV, Tafel slopes of 95.8, 39.6, and 33.8 mV dec -1 , and current density decays of 9, 6, and 6% after a 50 hour operation at an initial current density of 100 mA cm -2 , respectively. Substituting C with N in the coordination environment results in inferior HER catalytic efficiency and stability. Density functional theory calculations reveal that replacing carbon with nitrogen for coordination with the Mo SA on a carbon substrate of a higher N-doping level shifts the d-band center of Mo more negatively from the Fermi level, thereby increasing the hydrogen adsorption energy and thus decelerating the hydrogen desorption kinetics, giving consequent inferior HER activities.

25 ENERGY STORAGE↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to six O2- atoms to form distorted corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 11–17°. There are a spread of Mo–O bond distances ranging from 1.76–2.28 Å. In the second Mo6+ site, Mo6+ is bonded to six O2- atoms to form distorted corner-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 11–17°. There are a spread of Mo–O bond distances ranging from 1.76–2.28 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Mo6+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to two Mo6+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Mo6+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two Mo6+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Mo6+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one MoO2 sheet oriented in the (0, 0, 1) direction. Mo4+ is bonded to six equivalent O2- atoms to form edge-sharing MoO6 octahedra. There are four shorter (2.07 Å) and two longer (2.15 Å) Mo–O bond lengths. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Mo4+ is bonded to six equivalent O2- atoms to form edge-sharing MoO6 octahedra. There are four shorter (2.07 Å) and two longer (2.13 Å) Mo–O bond lengths. O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo3O8 by Materials Project

Mo3O8 crystallizes in the monoclinic Cm space group. The structure is two-dimensional and consists of two Mo3O8 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Mo+5.33+ sites. In the first Mo+5.33+ site, Mo+5.33+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 1.94–2.12 Å. In the second Mo+5.33+ site, Mo+5.33+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 1.90–2.07 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two equivalent Mo+5.33+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to two Mo+5.33+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to two equivalent Mo+5.33+ atoms. In the fourth O2- site, O2- is bonded in a water-like geometry to two Mo+5.33+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to three Mo+5.33+ atoms. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to three Mo+5.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Mo4+ sites. In the first Mo4+ site, Mo4+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.05–2.17 Å. In the second Mo4+ site, Mo4+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.05–2.17 Å. In the third Mo4+ site, Mo4+ is bonded to six O2- atoms to form distorted edge-sharing MoO6 octahedra. There are four shorter (2.18 Å) and two longer (2.19 Å) Mo–O bond lengths. In the fourth Mo4+ site, Mo4+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 1.96–2.07 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Mo4+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO3 by Materials Project

MoO3 crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two MoO3 sheets oriented in the (0, 0, 1) direction. Mo6+ is bonded to five O2- atoms to form corner-sharing MoO5 trigonal bipyramids. There is two shorter (1.78 Å) and three longer (2.04 Å) Mo–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Mo6+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Mo6+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoO2 by Materials Project

MoO2 is Hydrophilite-like structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Mo4+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Mo–O bond distances ranging from 2.02–2.12 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three equivalent Mo4+ atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo3O8 by Materials Project

Mo3O8 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two Mo3O8 sheets oriented in the (1, 0, 0) direction. there are two inequivalent Mo+5.33+ sites. In the first Mo+5.33+ site, Mo+5.33+ is bonded to six O2- atoms to form edge-sharing MoO6 octahedra. There is two shorter (1.94 Å) and four longer (1.96 Å) Mo–O bond length. In the second Mo+5.33+ site, Mo+5.33+ is bonded to six O2- atoms to form distorted edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 1.92–2.23 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in an L-shaped geometry to two equivalent Mo+5.33+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Mo+5.33+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to two Mo+5.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo2O3 by Materials Project

Mo2O3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Mo3+ sites. In the first Mo3+ site, Mo3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mo–O bond distances ranging from 2.08–2.31 Å. In the second Mo3+ site, Mo3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.96–2.57 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to six Mo3+ atoms to form OMo6 octahedra that share corners with four equivalent OMo5 square pyramids, edges with two equivalent OMo6 octahedra, and edges with six equivalent OMo5 square pyramids. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Mo3+ atoms. In the third O2- site, O2- is bonded to five Mo3+ atoms to form OMo5 square pyramids that share corners with two equivalent OMo6 octahedra, edges with three equivalent OMo6 octahedra, and edges with four equivalent OMo5 square pyramids. The corner-sharing octahedral tilt angles are 7°. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Mo3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mo3O8 by Materials Project

Mo3O8 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two Mo3O8 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Mo+5.33+ sites. In the first Mo+5.33+ site, Mo+5.33+ is bonded to six O2- atoms to form distorted edge-sharing MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 1.88–2.27 Å. In the second Mo+5.33+ site, Mo+5.33+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Mo–O bond distances ranging from 1.80–2.38 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two Mo+5.33+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to two equivalent Mo+5.33+ atoms. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Mo+5.33+ atoms. In the fourth O2- site, O2- is bonded in a water-like geometry to two Mo+5.33+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to three Mo+5.33+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to three Mo+5.33+ atoms.

36 MATERIALS SCIENCE↗