García-Baldoví Alberto, Cabrero Antonino María, Peng Lu, Tian Liang, Goberna-Ferrón Sara, Sastre Germán, García Hermenegildo, Antonietti Markus, Primo Ana
Instituto de Tecnología Química Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Universitat Politècnica de Valencia, Av. De los Naranjos s/n, 46022 Valencia, Spain.
Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany.
ACS Catal. 2025 May 21;15(11):9584-9596. doi: 10.1021/acscatal.5c00827. eCollection 2025 Jun 6.
Single metal atom-doped materials are gaining importance in photocatalysis since they offer potential maximum atom economy in a system. Herein, the preparation of poly-(heptazine imide) (PHI) carbon nitride materials having Cu or Co single atom sites or dual Cu and Co sites is reported. The materials have been characterized by chemical analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), while the single-atom nature of the metal dopants is supported by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption spectroscopy (XAS). The latter also shows a pronounced Cu-Co coordination. The resulting three metal-PHI samples were then explored as photocatalysts for the photocatalytic activation of CO reduction at various pressures from ambient to 35 bar. A drastic change in the products from CO and CH under ambient pressure to formic acid and methanol at high pressure was observed, with formic acid being the predominant product at intermediate pressures. The products derived from CO were firmly confirmed by C isotopic labeling monitored by gas chromatography-mass spectrometry (GC-MS) (gas products) or H NMR spectroscopy (liquid products). A synergy between Cu and Co was observed in the photocatalytic experiments, the activity following the order Co-Cu/PHI > Cu/PHI > Co/PHI and interpreted as derived from the complementary action of each cation, Cu promoting H activation better than Co and Co promoting hydrogenation of adsorbed CO at lower energy than Cu. These findings show the potential of synergistic effects among different single atoms on a semiconducting support to enhance photocatalytic activity. In addition, the data through light on the importance of pressure to control the product distribution in the photocatalytic CO hydrogenation toward the more valuable liquid products.
单金属原子掺杂材料在光催化领域正变得越来越重要，因为它们在体系中具有潜在的最大原子经济性。在此，报道了具有铜或钴单原子位点或铜钴双位点的聚（七嗪酰亚胺）（PHI）氮化碳材料的制备。这些材料通过化学分析、X射线衍射（XRD）和X射线光电子能谱（XPS）进行了表征，而金属掺杂剂的单原子性质则由高分辨率高角度环形暗场扫描透射电子显微镜（HAADF-STEM）和X射线吸收光谱（XAS）证实。后者还显示出明显的铜-钴配位。然后，将所得的三种金属-PHI样品作为光催化剂，用于在从环境压力到35巴的各种压力下光催化活化CO还原。观察到产物从环境压力下的CO和CH急剧变化为高压下的甲酸和甲醇，其中甲酸是中间压力下的主要产物。通过气相色谱-质谱联用仪（GC-MS）（气体产物）或1H NMR光谱（液体产物）监测C同位素标记，有力地证实了源自CO的产物。在光催化实验中观察到了铜和钴之间的协同作用，活性顺序为Co-Cu/PHI > Cu/PHI > Co/PHI，并解释为源于每个阳离子的互补作用，铜比钴更能促进H活化，而钴比铜在更低能量下促进吸附的CO氢化。这些发现表明了半导体载体上不同单原子之间协同效应在增强光催化活性方面的潜力。此外，这些数据揭示了压力对于控制光催化CO加氢生成更有价值的液体产物中产物分布的重要性。
