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Pt3O4 crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Pt+2.67+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.00 Å. O2- is bonded in a trigonal planar geometry to three equivalent Pt+2.67+ atoms.
Pt3O4 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Pt+2.67+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pt–O bond lengths are 2.37 Å. O2- is bonded in a 6-coordinate geometry to six equivalent Pt+2.67+ atoms.
Cd3(Pt3O4)10 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are thirteen inequivalent Pt+2.47+ sites. In the first Pt+2.47+ site, Pt+2.47+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Pt–O bond distances ranging from 1.99–2.06 Å. In the second Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.00 Å) and two longer (2.06 Å) Pt–O bond lengths. In the third Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.03 Å) and two longer (2.05 Å) Pt–O bond lengths. In the fourth Pt+2.47+ site, Pt+2.47+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.01 Å) and two longer (2.05 Å) Pt–O bond lengths. In the fifth Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.01 Å) and two longer (2.04 Å) Pt–O bond lengths. In the sixth Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.01 Å) and two longer (2.04 Å) Pt–O bond lengths. In the seventh Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.03 Å) and two longer (2.04 Å) Pt–O bond lengths. In the eighth Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.01 Å) and two longer (2.04 Å) Pt–O bond lengths. In the ninth Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. All Pt–O bond lengths are 2.04 Å. In the tenth Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. All Pt–O bond lengths are 2.04 Å. In the eleventh Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. All Pt–O bond lengths are 2.04 Å. In the twelfth Pt+2.47+ site, Pt+2.47+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. All Pt–O bond lengths are 2.01 Å. In the thirteenth Pt+2.47+ site, Pt+2.47+ is bonded in a square co-planar geometry to four O2- atoms. All Pt–O bond lengths are 2.01 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Cd–O bond lengths are 2.41 Å. In the second Cd2+ site, Cd2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.40 Å) and six longer (2.41 Å) Cd–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to three Pt+2.47+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Pt+2.47+ atoms. In the third O2- site, O2- is bonded to three Pt+2.47+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the fourth O2- site, O2- is bonded to three Pt+2.47+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the fifth O2- site, O2- is bonded to three Pt+2.47+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the sixth O2- site, O2- is bonded to three Pt+2.47+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the seventh O2- site, O2- is bonded in a trigonal planar geometry to three Pt+2.47+ atoms. In the eighth O2- site, O2- is bonded in a trigonal planar geometry to three Pt+2.47+ atoms. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to three Pt+2.47+ atoms. In the tenth O2- site, O2- is bonded to three Pt+2.47+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids.
Ni(Pt3O4)4 crystallizes in the cubic Fm-3 space group. The structure is three-dimensional. Pt+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.00 Å) and two longer (2.03 Å) Pt–O bond lengths. Ni2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ni–O bond lengths are 2.23 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Pt+2.50+ atoms. In the second O2- site, O2- is bonded to three equivalent Pt+2.50+ and one Ni2+ atom to form a mixture of edge and corner-sharing ONiPt3 trigonal pyramids.
Na3(Pt3O4)4 crystallizes in the cubic Fm-3 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Na–O bond lengths are 2.48 Å. In the second Na1+ site, Na1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.40 Å) and four longer (2.50 Å) Na–O bond lengths. Pt+2.42+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.02 Å) and two longer (2.04 Å) Pt–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two Na1+ and three equivalent Pt+2.42+ atoms to form ONa2Pt3 trigonal bipyramids that share corners with seven equivalent ONa2Pt3 trigonal bipyramids, corners with four equivalent ONaPt3 trigonal pyramids, edges with three equivalent ONa2Pt3 trigonal bipyramids, and edges with three equivalent ONaPt3 trigonal pyramids. In the second O2- site, O2- is bonded to one Na1+ and three equivalent Pt+2.42+ atoms to form ONaPt3 trigonal pyramids that share corners with four equivalent ONa2Pt3 trigonal bipyramids, corners with six equivalent ONaPt3 trigonal pyramids, and edges with three equivalent ONa2Pt3 trigonal bipyramids.
Ni(Pt3O4)4 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are five inequivalent Pt+2.50+ sites. In the first Pt+2.50+ site, Pt+2.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.03 Å. In the second Pt+2.50+ site, Pt+2.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.02 Å. In the third Pt+2.50+ site, Pt+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There are two shorter (2.00 Å) and two longer (2.04 Å) Pt–O bond lengths. In the fourth Pt+2.50+ site, Pt+2.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.03 Å. In the fifth Pt+2.50+ site, Pt+2.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.00 Å. Ni2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ni–O bond lengths are 2.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three Pt+2.50+ and one Ni2+ atom to form a mixture of corner and edge-sharing ONiPt3 trigonal pyramids. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Pt+2.50+ atoms.
Cd(Pt3O4)3 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are seven inequivalent Pt+2.44+ sites. In the first Pt+2.44+ site, Pt+2.44+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.04 Å. In the second Pt+2.44+ site, Pt+2.44+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.04 Å. In the third Pt+2.44+ site, Pt+2.44+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.02 Å. In the fourth Pt+2.44+ site, Pt+2.44+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.01 Å) and two longer (2.05 Å) Pt–O bond lengths. In the fifth Pt+2.44+ site, Pt+2.44+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.04 Å. In the sixth Pt+2.44+ site, Pt+2.44+ is bonded in a square co-planar geometry to four O2- atoms. All Pt–O bond lengths are 2.04 Å. In the seventh Pt+2.44+ site, Pt+2.44+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.01 Å. Cd2+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Cd–O bond lengths are 2.40 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to three Pt+2.44+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the second O2- site, O2- is bonded to three Pt+2.44+ and one Cd2+ atom to form a mixture of edge and corner-sharing OCdPt3 trigonal pyramids. In the third O2- site, O2- is bonded in a trigonal planar geometry to three Pt+2.44+ atoms.
TlTl(Pt3O4)2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of four thallium molecules and one Tl(Pt3O4)2 framework. In the Tl(Pt3O4)2 framework, Pt+2.33+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.05 Å. Tl1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Tl–O bond lengths are 2.42 Å. O2- is bonded to three equivalent Pt+2.33+ and one Tl1+ atom to form a mixture of distorted edge and corner-sharing OTlPt3 tetrahedra.
The platinum oxide Pt 3 O 4 exhibits metallic conductivity even though it contains square-planar PtO4 units, which in related oxides such as PtO are usually associated with insulating behavior. To identify the electronic origin of this anomalous metallicity, we performed a comprehensive first-principles study using the PBE and r 2 SCAN functionals together with Hubbard U corrections and spin-orbit coupling (SOC). Structural benchmarks show that r 2 SCAN with SOC and a moderate U value (<4 eV) reproduces the experimental lattice constants and formation enthalpy, whereas larger U values (~8 eV) destabilize the cubic structure. Across all functionals and U values considered in this work, Pt 3 O 4 remains metallic. Analyses of the projected density of states, band structures, charge-density isosurfaces, and bonding characteristics demonstrate that the dominant contribution to the metallic character originates from delocalized Pt–O–Pt hybridized antibonding states at the Fermi level. Direct Pt–Pt interactions are present but contribute less strongly to the conductivity. Bader charge analysis reveals only weak Pt charge disproportionation, consistent with mixed Pt II /Pt III character, and a small charge-transfer energy that prevents localization of the Pt 5d electrons even at elevated U. In contrast, PtO develops a Mott or charge-transfer gap under modest U despite having the same PtO 4 coordination environment. These findings demonstrate that persistent Pt–O–Pt covalency is the primary driver of metallicity in Pt 3 O 4 and support the view that this phase can remain conductive under oxygen reduction and oxygen evolution reaction conditions in fuel cell and electrolyzer environments.