Double-Phase Heterostructure within Fe-Doped Cu_2–xS Quantum Dots with Boosted Electrocatalytic Nitrogen Reduction

Abstract

Electrochemical nitrogen reduction reaction (NRR) is considered as one of the most promising methods for NH 3 synthesis under room temperature and ambient pressure. A grand challenge of NRR is the development of efficient electrocatalysts, for which the delicate nanostructuring of catalysts plays an important role. Herein, a series of Fedoped Cu 2−x S quantum dots (QDs) are synthesized with multiple active sites and interface engineering, in which the double-phase heterostructure plays a key role for boosting NRR activity. The yield of NH 3 was obviously improved with the increase of Fe content from 0 to 3% but started to decrease with Fe from 3 to 9%. The optimized Fe 3% −Cu 2−x S QDs show an outstanding NH 3 yield of 26.4 μg h −1 mg −1 cat at −0.7 V (vs the reversible hydrogen electrode), which is 5 times higher than that of Cu 2−x S QDs. More importantly, we observed that the highest NRR activity in Fe 3% −Cu 2−x S QDs was ascribed to the formation of an inherent double-phase heterostructure of Cu 2−x S/Cu 5 FeS 4 , whereas the complete conversion to single-phase Cu 5 FeS 4 with increased Fe doping (9%) resulted in the activity decrease. Further, N 2 temperature-programmed desorption and electrochemical impedance spectra characterizations confirm the stronger chemical adsorption of N 2 and faster charge transfer in the Cu 2−x S/Cu 5 FeS 4 QDs. A plausible mechanism was proposed for the double-phase Cu 2−x S/Cu 5 FeS 4 heterostructure, where the interface provides efficient charge transfer and more active sites of Cu, Fe, and S for the synergetic adsorption and activation of N 2 . Our work provides a simple strategy for the design of NRR electrocatalysts, which may also bring new inspiration for the preparation of the inherent double-phase heterostructure within other doped QDs.

Defect and interface engineering in metal sulfide catalysts for the electrocatalytic nitrogen reduction reaction: a review

“…By adding an Fe precursor during the synthesis of Cu 2− x S quantum dots (QD), Zhang et al synthesized Fe doped Cu 2− x S QD for the NRR. 92 It is found that by controlling the doping amount of Fe, double-phased Cu 2− x S/Cu 5 FeS 4 could be prepared (Fig. 8C).…”

Fe‐based catalysts for nitrogen reduction toward ammonia electrosynthesis under ambient conditions

“…108 Copyright 2021, American Chemical Society current of −1.6 mA and an NH 3 yield rate of 10.27 μg mg −1 h −1 , indicating excellent stability (Figure 12F). Mao et al 108 synthesized an Fe 3% −Cu 2−x S catalyst with multiple active sites via interface engineering. The NH 3 yield of the Fe 3% −Cu 2−x S catalyst is improved to 26.4 μg h −1 mg cat −1 (Figure 12G), corresponding to an FE of 3.1%.…”

“…During the 10 h test at −1.2 V, CNT@C 3 N 4 –Fe&Cu also exhibited a stable current of −1.6 mA and an NH 3 yield rate of 10.27 μg mg −1 h −1 , indicating excellent stability (Figure 12F). Mao et al 108 . synthesized an Fe 3% −Cu 2−x S catalyst with multiple active sites via interface engineering.…”

“…(H) 1 H NMR spectra for the qualitative isotope labeling test of Fe−Cu 2−x S QDs by using 14 N 2 and 15 N 2 . Reproduced with permission 108 . Copyright 2021, American Chemical Society…”

Ag–In–Zn–S Quantum Dot-Dominated Interface Kinetics in Ag–In–Zn–S/NiFe LDH Composites toward Efficient Photoassisted Electrocatalytic Water Splitting

“…Hydrogen energy holds great potential in renewable energy conversion and storage to meet the challenge of energy crisis, − for which novel hydrogen production methods by photocatalytic, electrocatalytic, and photoelectrochemical water splitting into hydrogen and oxygen have attracted tremendous research interest in terms of sustainability and carbon-free considerations . Compared to various methods, photoassisted electrocatalysis (P-EC) emerges as a rising star for hydrogen production by embedding photoactive species, such as plasmonic nanoparticles, , semiconductor nanostructures, , and carbon dots, , directly into various electrocatalysts.…”