Theoretical Insights into Heterogeneous (Photo)electrochemical CO₂Reduction

Abstract

Electrochemical and photoelectrochemical CO2 reduction technologies offer the promise of zero-carbon-emission renewable fuels needed for heavy-duty transportation. However, the inert nature of the CO2 molecule poses a fundamental challenge that must be overcome before efficient (photo)­electrochemical CO2 reduction at scale will be achieved. Optimal catalysts exhibit enduring stability, fast kinetics, high selectivity, and low manufacturing cost. Identifying catalytic mechanisms of CO2 reduction in (photo)­electrochemical systems could accelerate design of efficient catalysts. In recent decades, numerous theoretical studies have contributed to our understanding of CO2 reduction pathways and identifying rate-limiting steps. Although a significant body of work exists regarding homogeneous electrocatalysis for CO2 reduction, this review focuses specifically on the theory of heterogeneous (photo)­electrochemical reduction. We first give an overview of the relevant thermodynamics and semiconductor physics. We then introduce important, widely used theoretical techniques and modeling approaches to catalysis. Recent progress in elucidating mechanisms of heterogeneous (photo)­electrochemical CO2 reduction is discussed through the lens of two experimental systems: pyridine (Py)-catalyzed CO2 (photo)­electrochemical reduction at p-GaP photoelectrodes and electrochemical CO2 reduction at Cu electrodes. We close by proposing strategies and principles for the future design of (photo)­electrochemical catalysts to improve the selectivity and reaction kinetics of CO2 reduction.

Facile Morphology‐Tunable Preparation of CuS@MoS2 Heterostructures Based on Template Solvothermal Method

“…In order to preliminarily elucidate the relationship between CuS@MoS 2 morphology and its catalytic performance, a series of experiments regarding to CO 2 RR have been performed. CO 2 RR is an attractive technology known for its mild reaction condition and ease of operation, which benefits both the cure of environmental problems and realization of energy conversion . As the first step, linear sweep voltammetry (LSV) was conducted using the conventional three‐electrode electrochemical setup.…”

Sustainable Membrane‐Coated Electrodes for CO2 Electroreduction to Methanol in Alkaline Media

“…Table 2 presents the main results obtained in the CO 2 electroreduction experiments at À 1.0 V and À 1.5 V vs Ag/AgCl (À 0.18 V and À 0.68 V vs RHE, respectively) for the electrodes prepared in this work. Both the uncoated Cu/CS GDE and the MCEs led to methanol as main product, which is attributed to the alkaline environment, [5] as well as water swelling [11,48] and surface morphology. [12] Some Cu-based GDEs from literature also directed to methanol as main product are also reviewed in Table 2 in order to verify that the current densities generated with our working electrodes were of the same order of magnitude as those reported by other researchers in undivided cells at low overpotentials.…”

“…(11)], [67] (for water electrolysis that was competing with CO 2 electrolysis) H 2 Oþ2e À !H 2 þOH À ðE 0 ¼ À 0:83 VÞ (11) Still the information reported in literature about the methanol production mechanism in highly alkaline media is scarce. (11)], [67] (for water electrolysis that was competing with CO 2 electrolysis) H 2 Oþ2e À !H 2 þOH À ðE 0 ¼ À 0:83 VÞ (11) Still the information reported in literature about the methanol production mechanism in highly alkaline media is scarce.…”

“…Thus, assuming that CO 2 RR in alkaline media generates bicarbonate anions as Equation (12) 4 and CH 3 OH on a Cu catalyst. [11] Periasamy et al proposed a similar route for MeOH production, [47] by [Eqs. Then, an aldehyde was generated after another pair e À þH þ transferred.…”

“…[4] However, the electrochemical conversion of CO 2 is still a challenging subject. [8][9][10][11] Besides composition, surface structure and morphology also plays a relevant role in electrode performance. To this effect, it is important to improve the effectiveness and selectivity of complex electrocatalysts.…”