Tuning Unique Peapod‐Like Co(S_xSe_1–x)₂ Nanoparticles for Efficient Overall Water Splitting

Abstract

The development of efficient electrocatalysts with low cost and earth abundance for overall water splitting is very important in energy conversion. Although many electrocatalysts based on transition metal dichalcogenides have been developed, rational design and controllable synthesis of fine nanostructures with subtle morphologies and sequential chemical compositions related to these materials remains a challenge. This study reports a series of peapod-like composites with component-controllable Co(S x Se 1-x ) 2 nanoparticles encapsulated in carbon fibers, which are obtained by using Co(CO 3 ) 0.5 (OH)·0.11H 2 O nanowires as a precursor followed by coating carbon fiber and an adjustable sulfuration/selenylation process. Due to its increased exposure of active sites and improved charge and mass transport capability derived from the unique structure and morphology, the Co(S x Se 1-x ) 2 samples display favorable catalytic activities. It is found that Co(S 0.71 Se 0.29 ) 2 exhibits the best hydrogen evolution reaction (HER) performance and Co(S 0.22 Se 0.78 ) 2 shows the highest activity for the oxygen evolution reaction (OER). When using Co(S 0.71 Se 0.29 ) 2 as a cathode and Co(S 0.22 Se 0.78 ) 2 as an anode, it demonstrates a durable activity for overall water splitting to deliver 10 mA cm −2 at a cell voltage of 1.63 V, thus offering an attractive cost-effective earth abundant material system toward water splitting.

3D Architectures of Quaternary Co‐Ni‐S‐P/Graphene Hybrids as Highly Active and Stable Bifunctional Electrocatalysts for Overall Water Splitting

“…Highly efficient water electrolysis generally requires high-performance electrocatalysts with low overpotential, fast kinetics, and high stability. [9][10][11] Recently, transition-metal hydroxides, [7,12] phosphides, [8,[13][14][15][16] nitrides, [17,18] and chalcogenides [19][20][21][22] have been investigated as promising candidates for bifunctional electrocatalysts. [7,8] The search for earth-abundant, lowcost HER and OER electrocatalysts that are robust, have high activity and stability has triggered numerous efforts to replace noble metal-based materials.…”

“…However, the use of different type of electrocatalysts in an integrated electrolyzer is unacceptable, as it causes a mismatch in catalytic activity and stability in wide pH ranges. [21,23,27,28] For CoS 2 -based compounds, the electrocatalytic performance also strongly depends on the substitution into the cation and anion sites of the CoS 2 structure. [9] So, developing highly efficient bifunctional electrocatalysts for overall water splitting would have the advantages of reducing the economic costs and simplifying the water electrolyzing system.…”

Facile Synthesis of Sulfur‐Containing Transition Metal (Mn, Fe, Co, and Ni) (Hydr)oxides for Efficient Oxygen Evolution Reaction

“…[1][2][3] However, a practical application of the technology is hampered by the sluggish kinetics (high overpotential) of the anodic oxygen evolution reaction (OER). [24][25][26][27][28] However, MX a Y b type materials are usually prepared by multi-step methods, including high-temperature sulfurization, selenization, phosphorization, nitridation, or N 2 plasma treatment. [7][8][9][10] However, the scarcity and the high cost of iridium/ruthenium impede their large-scale utilization in industry.…”

“…[4,5] Various catalysts have been investigated to accelerate the kinetics and reduce the overpotential of OER, [3][4][5][6] and iridium/ruthenium based materials are among the most active catalysts for OER in acid conditions and also possess relatively high activity in basic conditions. [25][26][27][28] Thus, it is important to develop facile one-step wet chemical methods to provide an efficient access to MX a Y b type materials for OER.Herein, we report a facile one-step wet chemical method to prepare sulfur-containing transition metal (hydr)oxides by precipitation of transition metal nitrate solutions with an ammonium sulfide solution to result in efficient OER catalysts. Transition metal based materials have been intensively investigated to substitute iridium/ruthenium based materials due to their high abundance in the earth's crust and their lower costs.…”

“…[11][12][13] Diverse strategies have been developed to improve the OER performance of transition metal based materials. [24][25][26][27][28] The incorporation of a second element can optimize the electronic structure, create active sites, and facilitate the intermediate adsorption to achieve high electric conductivity, high exposure of active sites, and high intrinsic activity for decent electrochemical oxygen evolution performance. [23] Recent studies showed that transition metal based materials, MX a Y b (M = transition metal, X, Y=O, S, Se, N, and P), possess good OER performance.…”