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18 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Sub-Nanometer Nanoclusters of Copper Atop Single-Atom Copper Moieties toward Electrochemical CO 2 Hydrogenation to Methane

The electrochemical CO 2 reduction (eCO 2 R) offers a compelling route for converting CO 2 into value-added fuels and chemicals. Among CO 2 -derived products, methane (CH 4 ) occupies a distinct position, serving both as a key intermediate for emerging cascade electro-oxidation to oxygenates and as a strategically important extraterrestrial fuel that can be generated in situ from off-planet CO 2 resources. Although Cu-based catalysts capable of selectively producing CH 4 have been reported, they seldom sustain high selectivity at practically relevant current densities. Here, we created a single-step co-pyrolysis strategy toward generating and anchoring Cu sub-nanometer clusters (Cu SNC ) atop Cu-N x single-atom (SA) motifs embedded within N-doped carbon (NC), with controllable nanostructures through tuning of the synthesis parameters. Complementary spectroscopic analyses and density functional theory (DFT) calculations help reveal a structure−activity correlation that could guide the catalyst design. The Cu SNC @NC sample synthesized at 550 °C pyrolysis temperature (best described and modeled as Cu 3 -CuN 4 domains) represents the most effective combination of cluster size, metal-nitrogen coordination, and adsorption energetics needed to selectively promote CH 4 generation versus other eCO 2 R products. Incorporating pulsed electrolysis and hydrophobicity-modulated transport tuning at the triple-phase boundary (TPB) further enhanced CH 4 production achieving a partial CH 4 current density of ∼321 mA cm −2 , 53% Faradaic efficiency (FECH 4 ), and less than 4% combined FE for other eCO 2 R products, simplifying downstream CH 4 purification or upgrading. This work establishes generalizable principles for controlling Cu cluster atomicity and metal−nitrogen coordination, both of which are recognized determinants of CH 4 -efficient eCO 2 R.

CH4 production↗
DOE OSTI2026

Nitrogenated Graphene Quantum Dot-Derived Copper Single-Atom Catalyst for Oxygen Reduction Reaction

Despite the promise of fuel cells as sustainable energy conversion technologies, their widespread adoption is hindered by the high cost of platinum group metal (PGM) catalysts, particularly for catalyzing the oxygen reduction reaction (ORR) at the cathode. Here, we report copper-based single-atom catalysts (Cu-SACs) as cost-effective non-PGM alternatives for ORR. The catalysts were synthesized via simple pyrolysis of pyrene-derived amine-terminated graphene quantum dots (GQDs) in the presence of nitrogen and metal precursors. The abundant nitrogen functionality in GQDs effectively stabilized isolated Cu atoms during their conversion to porous carbon. A subsequent acid-washing step yielded a high density of atomically dispersed Cu active sites. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution scanning transmission electron microscopy (HR-STEM) confirmed the effective incorporation of isolated Cu atoms into the carbon matrix through copper–nitrogen (Cu-N) coordination. Electrochemical measurements revealed excellent ORR activity with a dominant four-electron pathway. This synthetic strategy provides a practical route to developing economically viable, non-precious metal catalysts.

catalysts↗
DOE OSTI2020

Materials Data on CuN by Materials Project

CuN is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Cu3+ is bonded to four equivalent N3- atoms to form corner-sharing CuN4 tetrahedra. All Cu–N bond lengths are 1.92 Å. N3- is bonded to four equivalent Cu3+ atoms to form corner-sharing NCu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3N by Materials Project

Cu3N is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Cu1+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Cu–N bond lengths are 2.47 Å. N3- is bonded to twelve equivalent Cu1+ atoms to form a mixture of face and corner-sharing NCu12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3N by Materials Project

Cu3N is alpha Rhenium trioxide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Cu1+ is bonded in a linear geometry to two equivalent N3- atoms. Both Cu–N bond lengths are 1.91 Å. N3- is bonded to six equivalent Cu1+ atoms to form corner-sharing NCu6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN3 by Materials Project

CuN3 crystallizes in the tetragonal I4_1/a space group. The structure is one-dimensional and consists of eight CuN3 ribbons oriented in the (0, 0, 1) direction. Cu1+ is bonded in a linear geometry to two equivalent N+0.33- atoms. Both Cu–N bond lengths are 1.84 Å. There are two inequivalent N+0.33- sites. In the first N+0.33- site, N+0.33- is bonded in a distorted bent 150 degrees geometry to one Cu1+ and one N+0.33- atom. The N–N bond length is 1.18 Å. In the second N+0.33- site, N+0.33- is bonded in a linear geometry to two equivalent N+0.33- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN3 by Materials Project

CuN3 crystallizes in the tetragonal I4_1/a space group. The structure is one-dimensional and consists of eight CuN3 ribbons oriented in the (0, 0, 1) direction. Cu1+ is bonded in a linear geometry to two equivalent N+0.33- atoms. Both Cu–N bond lengths are 1.84 Å. There are two inequivalent N+0.33- sites. In the first N+0.33- site, N+0.33- is bonded in a linear geometry to two equivalent N+0.33- atoms. Both N–N bond lengths are 1.18 Å. In the second N+0.33- site, N+0.33- is bonded in a 1-coordinate geometry to one Cu1+ and one N+0.33- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN6 by Materials Project

CuN6 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Cu2+ is bonded to six N+0.33- atoms to form distorted edge-sharing CuN6 octahedra. There are a spread of Cu–N bond distances ranging from 2.01–2.75 Å. There are six inequivalent N+0.33- sites. In the first N+0.33- site, N+0.33- is bonded in a linear geometry to two N+0.33- atoms. There is one shorter (1.16 Å) and one longer (1.23 Å) N–N bond length. In the second N+0.33- site, N+0.33- is bonded in a bent 150 degrees geometry to one Cu2+ and one N+0.33- atom. The N–N bond length is 1.16 Å. In the third N+0.33- site, N+0.33- is bonded in a distorted trigonal planar geometry to two equivalent Cu2+ and one N+0.33- atom. The N–N bond length is 1.22 Å. In the fourth N+0.33- site, N+0.33- is bonded in a 4-coordinate geometry to three equivalent Cu2+ and one N+0.33- atom. In the fifth N+0.33- site, N+0.33- is bonded in a single-bond geometry to one N+0.33- atom. In the sixth N+0.33- site, N+0.33- is bonded in a linear geometry to two N+0.33- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN by Materials Project

CuN crystallizes in the monoclinic Pm space group. The structure is one-dimensional and consists of two CuN ribbons oriented in the (1, 0, 1) direction. Cu3+ is bonded in a linear geometry to two equivalent N3- atoms. There is one shorter (1.72 Å) and one longer (1.73 Å) Cu–N bond length. N3- is bonded in a linear geometry to two equivalent Cu3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN by Materials Project

CuN is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Cu3+ is bonded to six equivalent N3- atoms to form a mixture of edge and corner-sharing CuN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Cu–N bond lengths are 2.08 Å. N3- is bonded to six equivalent Cu3+ atoms to form a mixture of edge and corner-sharing NCu6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN by Materials Project

CuN is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Cu3+ is bonded in a body-centered cubic geometry to eight equivalent N3- atoms. All Cu–N bond lengths are 2.26 Å. N3- is bonded in a body-centered cubic geometry to eight equivalent Cu3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3N by Materials Project

Cu3N crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two Cu3N sheets oriented in the (0, 0, 1) direction. there are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Cu–N bond lengths are 2.01 Å. In the second Cu1+ site, Cu1+ is bonded in a single-bond geometry to one N3- atom. The Cu–N bond length is 1.96 Å. N3- is bonded to six Cu1+ atoms to form a mixture of edge and corner-sharing NCu6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu2N by Materials Project

Cu2N crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded in a linear geometry to two equivalent N3- atoms. Both Cu–N bond lengths are 1.88 Å. In the second Cu+1.50+ site, Cu+1.50+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Cu–N bond lengths are 2.07 Å. N3- is bonded to six Cu+1.50+ atoms to form a mixture of corner and edge-sharing NCu6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3N by Materials Project

Cu3N crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional and consists of one ammonia molecule, eight copper molecules, and one Cu16N7 framework. In the Cu16N7 framework, there are twelve inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.85 Å) and one longer (1.87 Å) Cu–N bond length. In the second Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.85 Å) and one longer (1.87 Å) Cu–N bond length. In the third Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.85 Å) and one longer (1.87 Å) Cu–N bond length. In the fourth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.82 Å) and one longer (1.89 Å) Cu–N bond length. In the fifth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.82 Å) and one longer (1.89 Å) Cu–N bond length. In the sixth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.83 Å) and one longer (1.90 Å) Cu–N bond length. In the seventh Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.83 Å) and one longer (1.90 Å) Cu–N bond length. In the eighth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.83 Å) and one longer (1.90 Å) Cu–N bond length. In the ninth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.82 Å) and one longer (1.90 Å) Cu–N bond length. In the tenth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.82 Å) and one longer (1.90 Å) Cu–N bond length. In the eleventh Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.82 Å) and one longer (1.90 Å) Cu–N bond length. In the twelfth Cu1+ site, Cu1+ is bonded in a linear geometry to two N3- atoms. There is one shorter (1.82 Å) and one longer (1.90 Å) Cu–N bond length. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a square co-planar geometry to four Cu1+ atoms. In the second N3- site, N3- is bonded in a square co-planar geometry to four Cu1+ atoms. In the third N3- site, N3- is bonded in a square co-planar geometry to four Cu1+ atoms. In the fourth N3- site, N3- is bonded in an octahedral geometry to six Cu1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuN by Materials Project

CuN crystallizes in the monoclinic P2/m space group. The structure is one-dimensional and consists of two CuN ribbons oriented in the (0, 1, 0) direction. Cu3+ is bonded in an L-shaped geometry to two equivalent N3- atoms. Both Cu–N bond lengths are 2.01 Å. N3- is bonded in a 3-coordinate geometry to two equivalent Cu3+ and one N3- atom. The N–N bond length is 1.18 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3N by Materials Project

Cu3N crystallizes in the orthorhombic Immm space group. The structure is two-dimensional and consists of two Cu3N sheets oriented in the (0, 0, 1) direction. there are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in an L-shaped geometry to two equivalent N3- atoms. Both Cu–N bond lengths are 2.05 Å. In the second Cu1+ site, Cu1+ is bonded in a linear geometry to two equivalent N3- atoms. Both Cu–N bond lengths are 1.89 Å. N3- is bonded to six Cu1+ atoms to form a mixture of edge and corner-sharing NCu6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu3N by Materials Project

Cu3N is trigonal omega-like structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a 3-coordinate geometry to three equivalent Cu1+ and three equivalent N3- atoms. All Cu–Cu bond lengths are 2.56 Å. All Cu–N bond lengths are 2.04 Å. In the second Cu1+ site, Cu1+ is bonded in a 6-coordinate geometry to six equivalent Cu1+ atoms. N3- is bonded to six equivalent Cu1+ atoms to form edge-sharing NCu6 octahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu10N3 by Materials Project

Cu10N3 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are three inequivalent Cu sites. In the first Cu site, Cu is bonded in a linear geometry to one Cu and two N atoms. The Cu–Cu bond length is 2.66 Å. There is one shorter (1.90 Å) and one longer (1.91 Å) Cu–N bond length. In the second Cu site, Cu is bonded in a linear geometry to two equivalent Cu and two equivalent N atoms. Both Cu–Cu bond lengths are 2.71 Å. Both Cu–N bond lengths are 1.94 Å. In the third Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with six equivalent CuCu12 cuboctahedra and faces with eight NCu6 octahedra. There are two inequivalent N sites. In the first N site, N is bonded to six Cu atoms to form NCu6 octahedra that share corners with six NCu6 octahedra and faces with three equivalent CuCu12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the second N site, N is bonded to six equivalent Cu atoms to form NCu6 octahedra that share corners with six equivalent NCu6 octahedra and faces with two equivalent CuCu12 cuboctahedra. The corner-sharing octahedral tilt angles are 4°.

36 MATERIALS SCIENCE↗