Therefore, it can speculate that the active sites of the catalyst towards the process locate at the interface of FeS 2 and NiS. RHE) and extremely low current density of 1.0 mA cm −2 at −0.68 V ( vs. The NiS nanocrystal shows a more negative onset potential at −0.5 V ( vs. RHE) and a maximum current density of 4.2 mA cm −2 at −0.68 V ( vs. The FeS 2 nanocrystal shows a negative onset potential at −0.45 V ( vs. As a comparison, we synthesized the single FeS 2 and NiS nanocrystals and applied in CO 2RR, respectively. The following experiments reveal the insight mechanism of CO 2RR catalyzed by FeS 2/NiS nanocomposite. There is no obvious degradation of the electrocatalyst after the long-time test. The stability test of FeS 2/NiS nanocomposite was performed for 4 hours, showing a stable current density of 3.1 mA cm −2 at −0.6 V ( vs. FeS 2/NiS nanocomposite displays incomparable operation in its low overpotential of 280 mV and high selectivity with a CH 3OH FE up to 64% at the potential of −0.6 V ( vs. Herein, we fabricated a low-cost FeS 2/NiS nanocomposite by traditional hydrothermal method as an excellent electrocatalyst. 29 Therefore, it is urgent to seek for a highly active, selective and effective catalyst towards electroreduction CO 2 to CH 3OH. reported that electrodeposited cuprous oxide thin films could directly reduce CO 2 to CH 3OH with a rate of 43 μmol cm −2 h −1 and low FE of 38%. Among them, copper is demonstrated as the effective catalyst for the electroreduction of CO 2 to hydrocarbon and alcohols. 19 Fe, 20 Ni, 21 Cu 22 and their associated complexes 23–26 have been widely investigated in the yield of CO 2RR as their rich distribution and low cost. firstly observed Teflon-supported Ru electrodes could selectively reduce CO 2 to CH 3OH with a low faradaic efficiency (FE) of 42%.
Significant efforts towards selectively converting CO 2 into CH 3OH have been made since early 1983 over semiconductor materials (p-GaP and p-GaAs) with a low current density (<1 mA cm −2).
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However, the 6 e − process of CO 2 reduction to form CH 3OH over the full reaction is kinetically unfavorable. 16,17 The standard potential of CO 2 electroreduction to CH 3OH is only 0.016 V ( vs. 15 Besides, CH 3OH with high energy density can be stored as liquid under ambient conditions. 14 Moreover, the main product from noble metals is carbon monoxide (CO), which leads to the second pollution at the cost of CO 2 consumption.ĬH 3OH, as an ideal chemical, is an important intermediate of paint, plastics, and other common products. 5 Among them, Au, 6–9 Ag, 1,10,11 and Pd 12,13 have been explored comprehensively, while the expensive price limits the substantial application of noble metals in industry. Transition metals are commonly proposed in CO 2 reduction reaction (CO 2RR) because of their vacant orbits and active d electrons. 5 The complex products increase the challenges towards generating target product. As for the selectivity, in addition to the major side reaction hydrogen evolution reaction (HER), the direct electroreduction of CO 2 in aqueous solution is able to generate diversiform carbon-containing chemicals. 4,5 The high overpotential increases the consumption of energy and makes it difficult to achieve the sustainable transformation of CO 2.
1–3 However, the main defects of electroreduction CO 2 are the high overpotential required to drive the reaction, the low selectivity towards various products and the high cost of catalysts. Introduction Electrochemical reduction of CO 2 to carbon-containing fuels is a feasible process which is conducive to solving the serious environmental problems caused by excess CO 2 such as iceberg melting, sea level rise and coastal delta subsidence. The active sites are located at the interface between FeS 2 and NiS which can effectively suppress the side reaction hydrogen evolution reaction and facilitate the CO 2 reduction reaction. The high selectivity towards CO 2 electroreduction to CH 3OH may be attributed to the special ladder structure of the FeS 2/NiS nanocomposite. The FeS 2/NiS nanocomposite electrocatalyst exhibits a stable current density of 3.1 mA cm −2 over a 4 hour stability test. In this work, we introduce a FeS 2/NiS nanocomposite electrocatalyst synthesized by traditional hydrothermal method, which selectively reduces CO 2 to CH 3OH with an unprecedented overpotential of 280 mV and a high faradaic efficiency up to 64% at the potential of −0.6 V vs. Electrochemical reduction of carbon dioxide (CO 2) to methanol (CH 3OH) catalyzed by transition metals has been proved feasible and effective in aqueous electrolytes.
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