Direct conversion of carbon dioxide to formic acid at thermodynamic equilibrium is an advantage of enzymatic catalysis, hardly replicated by synthetic analogs, but of high priority for carbon-neutral energy schemes. The bio-mimetic potential of totally inorganic Pd@TiO₂ nanoparticles is envisioned herein in combination with Single Walled Carbon NanoHorns (SWCNHs). The high surface nano-carbon entanglement templates a wide distribution of “hard-soft” bimetallic sites where the small Pd nanoparticles (1.5 nm) are shielded within the TiO₂ phase (Pd@TiO₂), while being electrically wired to the electrode by the nanocarbon support. This hybrid electrocatalyst activates CO₂ reduction to formic acid at near zero overpotential in the aqueous phase (onset potential at E < −0.05 V vs. RHE, pH = 7.4), while being able to evolve hydrogen via sequential formic acid dehydrogenation. The net result hints at a unique CO₂ “circular catalysis” where formic acid versus H₂ selectivity is addressable by flow-reactor technology.

中文翻译：

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Pd @ TiO ₂ /碳纳米角电催化剂：可逆的CO ₂加氢成甲酸†

在热力学平衡条件下将二氧化碳直接转化为甲酸是酶催化的优势，几乎不能被合成类似物复制，但是对于碳中和能源计划具有很高的优先级。本文设想了与单壁碳纳米角（SWCNHs）组合的完全无机的Pd @ TiO ₂纳米颗粒的仿生潜力。高表面纳米碳缠结模板分布着广泛的“硬-软”双金属位点，其中小的Pd纳米颗粒（1.5 nm）在TiO ₂相（Pd @ TiO ₂）内被屏蔽，同时通过纳米碳载体。这种杂化电催化剂可活化CO ₂在水相中接近零的超电势下还原成甲酸（E <-0.05 V相对于RHE的起始电势，pH = 7.4），同时能够通过顺序的甲酸脱氢生成氢。最终结果暗示了独特的CO ₂ “循环催化”，其中甲酸对H _2的选择性可以通过流动反应器技术解决。