コバルトリン化物（CoP）表面における水素結合の化学量論・熱化学的解析
Cobalt phosphide (CoP) is a candidate earth-abundant catalyst for the hydrogen evolution reaction (HER). This study experimentally characterized the stoichiometry and thermochemistry of hydrogen atoms bound to CoP, using both acid-pretreated mesoscale CoP particles and colloidal CoP nanoparticles. H2 treatment introduced approximately 0.2 H per CoP formula unit, corresponding to roughly one H per surface Co or P atom. Quantification relied on alkyne hydrogenation and H-atom transfer reactions with phenoxy radicals. The distribution of binding free energies for surface H atoms was estimated at approximately 51–66 kcal mol⁻¹ (ΔG° ≈ 0 to −0.7 eV vs H). Operando X-ray absorption spectroscopy revealed a slight lattice expansion under H-flow with no appreciable shift in the effective nuclear charge of Co. These findings reframe the picture of catalytically active CoP as a material carrying a substantial reservoir of reactive hydrogen atoms, with implications for its electrocatalytic performance and a methodological framework applicable to other transition metal phosphide materials.
H2 treatment loads reactive H atoms onto surface Co and P sites of CoP. These atoms participate in alkyne hydrogenation and H-atom transfer to phenoxy radicals. Operando spectroscopy indicates lattice expansion upon H-loading without altering Co oxidation state, suggesting interstitial or surface H incorporation drives catalytic activity.
This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).
See also:
https://h2-papers.org/en/papers/31479259