Selectivity of nanocrystalline anatase electrodes with different preferential surface orientation in formaldehyde reduction was assessed as a model of oxide-based catalyst for electrochemical CO₂ valuation. Cathodic behavior of TiO₂ (anatase)-based electrodes observed in formaldehyde reaction integrates, in fact, several processes including hydrogen evolution, formaldehyde reduction, and proton insertion into anatase structure. The electrochemical activity of the anatase-based cathodes is, regardless of the surface orientation, dominated by proton insertion. The proton insertion is more pronounced on {001}-oriented anatase than on {101}-oriented nanocrystals due to anisotropy of the proton transport in the anatase which is more facile in the (001) direction. Aside from the proton insertion, both anatase orientations also differ in selectivity in the formaldehyde reduction. While {101} surface orientation produces primarily hydrogen and methanol, the same process on {001}-oriented surfaces shows the ability to produce aside of methanol also hydrocarbons most likely methane. The overall activity towards the reduction of organics is, however, lower than that of metals.

Graphical Abstract

在甲醛还原中具有不同优先表面取向的纳米晶锐钛矿电极的选择性被评估为用于电化学CO ₂评估的基于氧化物的催化剂模型。TiO _2的阴极行为实际上，在甲醛反应中观察到的基于（锐钛矿）的电极整合了多个过程，包括析氢，甲醛还原以及质子插入锐钛矿结构中。不论表面取向如何，基于锐钛矿的阴极的电化学活性均以质子插入为主。与在{101}取向的纳米晶体上相比，在{001}取向的锐钛矿上质子的插入更明显，这是由于在（001）方向上更容易实现的在锐钛矿中质子传输的各向异性。除质子插入外，两种锐钛矿取向在甲醛还原中的选择性也不同。尽管{101}的表面取向主要产生氢和甲醇，但在{001}取向的表面上的相同过程显示出除了甲醇之外还可以产生烃类（最可能是甲烷）的能力。

图形概要