Electrochemical reduction of Co2 on metal oxides
Abstract
The continuous burning of fossil fuels is leading to an alarming increase of the atmospheric carbon
dioxide (CO2) concentration, which has been currently reported to be as high as 414 ppm [1]. Among
the different available strategies to address both electricity demands and carbon emissions, the
electrochemical reduction of CO2 into value-added products, which is a multistep reaction process
involving different pathways [2], is considered as an attractive method that is able to store energy from
intermittent renewable sources [3]. Moreover, this approach represents an environmentally friendly
way of recycling CO2 as well as its transformation into fuels and chemicals such as carbon monoxide
(CO), formic acid (HCOOH), methanol (CH3OH), methane (CH4) and ethylene (C2H4) at mild conditions
[4, 5]. However, the main challenge of this technology is associated with the electrocatalytic material
used. Thus, the development of highly active, durable, efficient and selective electrocatalysts is still an
important issue to be overcome for the industrial implementation of this process [6]. Different metal
electrocatalysts such as Au, Ag (CO production) [7], Sn, Pb, Bi, In (HCOOH/HCOO- formation) [8], and
Cu (alcohols and hydrocarbons) [9, 10] are well-known selective materials for the electrochemical
transformation of CO2. Nevertheless, the efficiency and selectivity of the process still need to be
improved. Hence, the use of metal oxides-based electrocatalysts has attracted the interest of the
research community due to the possibility of improving catalytic activity, electrode durability and
reaction selectivity (regularly represented by the Faradaic efficiency, FE) [2]. The key aspects that lead
to an enhanced performance are morphological features (i.e. roughness) and the role of oxygen in
reaction mechanisms, among others [11]. Some representative results of CO2 electroreduction at
metal oxides electrocatalysts are presented in Table 1 [12-14].