High‐entropy materials, composed of five or more elements in near‐equiatomic percentage, have been attracting tremendous interests due to their advantageous properties in a variety of applications. Recently, electrocatalysis on high‐entropy alloys (HEAs) and high‐entropy compounds (HECs) has emerged as a new and promising material owing to the tailored composition and the disordered configuration of HEAs and HECs. Though extensive efforts have been devoted to investigating the catalytic nature of HEAs and HECs, the details related to the active sites and intrinsic activity of such catalysts still remain uncertain due to the complexity of the multicomponent systems. In this review, the recent progress of HEAs and HECs is systematically reviewed in terms of their synthetic strategies and electrocatalytic applications. Importantly, the computationally assisted methods (e.g., density functional theory [DFT]) are also presented to discover and design the optimum HEA‐ and HEC‐based catalysts. Subsequently, the applications of HEAs and HECs in electrocatalytic energy conversion reactions will be discussed, including hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, methanol oxidation reaction, and ethanol oxidation reaction (EOR). Moreover, the prospects and future opportunities for this research field are cautiously discussed. A series of upcoming challenges and questions are thoroughly proposed from the experimental and theoretical aspects as well as other future applications in electrocatalysis.
The catalyst innovation that aims at noble‐metal‐free substitutes is one key aspect for future sustainable hydrogen energy deployment. In this paper, a nickel cobalt sulfoselenide/black phosphorus heterostructure (NiCoSe|S/BP) was fabricated to realize the highly active and durable water electrolysis through interface and valence dual‐engineering. The NiCoSe|S/BP nanostructure was constructed by in‐situ growing NiCo hydroxide nanosheet arrays on few‐layer BP and subsequently one‐step sulfoselenization by SeS2. Besides the conductive merit of BP substrate, holes in p‐type BP are capable of oxidizing the Co2+ to high‐valence and electron‐accepting Co3+, benefiting the oxygen evolution reaction (OER). Meanwhile, Ni3+/Ni2+ ratio in the heterostructure is reduced to maintain the electrical neutrality, which corresponds to the increased electron‐donating character for boosting hydrogen evolution reaction (HER). As for HER and OER, the heterostructured NiCoSe|S/BP electrocatalyst exhibits small overpotentials of 172 and 285 mV at 10 mA cm−2 (η10) in alkaline media, respectively. And overall water splitting has been achieved at a low cell potential of 1.67 V at η10 with high stability. Molecular sensing and density functional theory (DFT) calculations are further proposed for understanding the rate‐determine steps and enhanced catalytic mechanism. The investigation presents a deep‐seated perception for the electrocatalytic performance enhancement of BP‐based heterostructure.
Metal phosphorus trichalcogenide (MPX3) materials have aroused substantial curiosity in the evolution of electrochemical storage devices due to their environment-friendliness and advantageous X-P synergic effects. The interesting intercalation properties generated due to the presence of wide van der Waals gaps along with high theoretical specific capacity pose MPX3 as a potential host electrode in lithium batteries. Herein, we synthesized two-dimensional iron thio-phosphate (FePS3) nanoflakes via a salt-template synthesis method, using low-temperature time synthesis conditions in single step. The electrochemical application of FePS3 has been explored through the construction of a high-capacity lithium primary battery (LPB) coin cell with FePS3 nanoflakes as the cathode. The galvanostatic discharge studies on the assembled LPB exhibit a high specific capacity of ~1791 mAh g−1 and high energy density of ~2500 Wh Kg−1 along with a power density of ~5226 W Kg−1, some of the highest reported values, indicating FePS3’s potential in low-cost primary batteries. A mechanistic insight into the observed three-staged discharge mechanism of the FePS3-based primary cell resulting in the high capacity is provided, and the findings are supported via post-mortem analyses at the electrode scale, using both electrochemical- as well as photoelectron spectroscopy-based studies.
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