2D FeS_x Nanosheets by Atomic Layer Deposition: Electrocatalytic Properties for the Hydrogen Evolution Reaction

Abstract

2‐dimensional FeSx nanosheets of different sizes are synthesized by applying different numbers of atomic layer deposition (ALD) cycles on TiO2 nanotube layers and graphite sheets as supporting materials and used as an electrocatalyst for the hydrogen evolution reaction (HER). The electrochemical results confirm electrocatalytic activity in alkaline media with outstanding long‐term stability (>65 h) and enhanced catalytic activity, reflected by a notable drop in the initial HER overpotential value (up to 26 %). By using a range of characterization techniques, the origin of the enhanced catalytic activity was found to be caused by the synergistic interplay between in situ morphological and compositional changes in the 2D FeSx nanosheets during HER. Under the application of a cathodic potential in alkaline media, the as‐synthesized 2D FeSx nanosheets transformed into iron oxyhydroxide‐iron oxysulfide core‐shell nanoparticles, which exhibited a higher active catalytic surface and newly created Fe‐based HER catalytic sites.

Dual Role of Microbe–FexSy Interaction to Drive Perfluorooctanoic Acid Multipath Chain Reaction Decay Cycles and Secondary Minerals-Ions (Fe2+/Fe3+) Transformation Cycles

“…The XPS spectra of Cell&(Fe x S y &QS) in the four types of PFOA-ion occurrence environments before and after the reaction were presented in Figure . Fe­(II)–S and Fe­(III)–S were credited with causing the 707.0 and 710.6 eV Fe 2p3/2 peak, as well 719.7 and 724.2 eV Fe 2p1/2 peak, respectively. , Fe­(III)–O was responsible for the Fe 2p3/2 peak at 713.1 eV and Fe 2p1/2 peak 727.0 eV. , Fe­(II)–S (51.81%), Fe­(III)–S (29.26%), and Fe­(III)–O (18.93%) were detected in the range of Fe 2p before the reaction (Figure a).…”

“…Fe(II)−S and Fe(III)−S were credited with causing the 707.0 and 710.6 eV Fe 2p3/2 peak, as well 719.7 and 724.2 eV Fe 2p1/2 peak, respectively. 30,31 Fe(III)−O was responsible for the Fe 2p3/ 2 peak at 713.1 eV and Fe 2p1/2 peak 727.0 eV. 30,32 2− after the reaction in different PFOA-ion occurrence environments (Figure 4c,e,g,i).…”

Fe(IV)═O/Fe(V)═O and [FeaqIVO]2+/[FeaqVO]3+ Cooperating with Free Radicals Induced High-Rate Sulfamethoxazole-Cr(VI) Simultaneous Removal in a Fe7S8-Persulfate Micro/Nanocatalytic System

“…Three peaks of Fe­(III)-O (713.1 and 727.0 eV), Fe­(III)-S (710.4 and 724.0 eV), and Fe­(II)-S (706.8 and 719.7 eV) were fitted to the high-resolution spectrum of Fe 2p (Figure g and Table S3). − The proportion of the Fe­(III)-O peak increased from 22.0 to 22.6%, and the proportion of the Fe­(III)-S peak decreased from 60.7 to 58.9% after the reaction in the sole Fe 7 S 8 system, indicating that secondary iron-oxide minerals were generated during the reaction. Nevertheless, the proportion of the Fe­(III)-O peak decreases from 22.0 to 20.5%, the proportion of the Fe­(III)-S peak decreases from 60.7 to 58.2%, and the proportion of the Fe­(II)-S peak increases from 17.3 to 21.3% in the Fe 7 S 8 –PS system, demonstrating that PS promotes the Fe 3+ /Fe 2+ cycle and generates more Fe 2+ .…”

Insight into the intrinsic activity of various transition metal sulfides for efficient hydrogen evolution reaction

“…FeS 2 nanosheets transform morphologically and experience a chemical composition change to yield FeOOH, boosting the HER process. 46 CoS x surface reconstruction leads to the CoOOH as a new active site to enhance HER activity. 47 NiS generates a NiOOH phase during alkaline HER, leading to improved HER performance.…”