The deposition of metal oxides is essential to the fabrication of numerous multicomponent solid-state devices and catalysts. However, the reproducible formation of homogeneous metal oxide films or of nanoparticle dispersions at solid interfaces remains an ongoing challenge. Here we report that molecular hexaniobate cluster anion complexes of structurally and electronically distinct fragments of cubic-spinel and monoclinic Co₃O₄ can serve as tractable yet well-defined functional analogues of bulk cobalt oxide. Notably, the energies of the highest-occupied and lowest-unoccupied molecular orbitals (HOMO and LUMO) of the molecular complexes, 1, closely match the valence- and conduction-band (VB and CB) energies of the parent bulk oxides. Use of 1 as a molecular analogue of the parent oxides is demonstrated by its remarkably simple deployment as a cocatalyst for direct Z-scheme reduction of CO₂ by solar light and water. Namely, evaporation of an aqueous solution of 1 on TiO₂-coated fluorinated tin oxide windows (TiO₂/FTO), immersion in wet acetonitrile, and irradiation by simulated solar light under an atmosphere of CO₂ give H₂, CO, and CH₄ in ratios nearly identical to those obtained using 20 nm spinel-Co₃O₄ nanocrystals, but 15 times more rapidly on a Co basis and more rapidly overall than other reported systems. Detailed investigation of the photocatalytic properties of 1 on TiO₂/FTO includes confirmation of a direct Z-scheme charge-carrier migration pathway by in situ irradiated X-ray photoelectron spectroscopy. More generally, the findings point to a potentially important new role for coordination chemistry that bridges the conceptual divide between molecular and solid-state science.

中文翻译：

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钴氧化物片段的可溶性复合物将散装材料独特的 CO2 光还原活性带入分子科学的灵活领域

金属氧化物的沉积对于制造众多多组分固态器件和催化剂至关重要。然而，在固体界面上可重复地形成均匀的金属氧化物薄膜或纳米颗粒分散体仍然是一个持续的挑战。在这里，我们报告了立方尖晶石和单斜 Co ₃ O ₄的结构和电子上不同的碎片的分子六铌酸盐簇阴离子复合物可以作为块状氧化钴的易处理但定义明确的功能类似物。值得注意的是，分子复合物1的最高占据和最低未占据分子轨道（HOMO 和 LUMO）的能量与母体氧化物的价带和导带（VB 和 CB）能量密切匹配。使用1作为母体氧化物的分子类似物，其作为助催化剂的部署非常简单，可用于通过太阳光和水直接 Z 型还原 CO ₂。即，在 TiO ₂涂覆的氟化氧化锡窗 (TiO ₂ /FTO)上蒸发1的水溶液，浸入湿乙腈中，并在 CO ₂气氛下模拟太阳光照射得到 H ₂、CO 和 CH ₄的比率几乎与使用 20 nm 尖晶石-Co ₃ O ₄获得的比率相同纳米晶体，但以 Co 为基础的速度快 15 倍，整体速度比其他报道的系统快。对1在 TiO ₂ /FTO上的光催化性能的详细研究包括通过原位辐射 X 射线光电子能谱确认直接 Z 型电荷载流子迁移途径。更一般地说，这些发现指出了配位化学的潜在重要新作用，它弥合了分子科学和固态科学之间的概念鸿沟。