Superhydrophobic conjugated microporous polymers show good selectivity, fast adsorption kinetics, excellent recyclability and absorbencies for a wide range of organic solvents and oils, which make them the promising candidates for potential applications, including liquid-liquid separation, water treatment and so on.Superhydrophobic surfaces (water contact angle (CA) larger than 150 ) have generated extensive commercial and academic interest. [1][2][3][4][5][6][7] In recent years, there has been an increased interest in generation and utilization of the surface superhydrophobicity of a solid for direct separation or selective adsorption of oil or hydrophobic organic solvents from water. The first example for oil-water separation by using superhydrophobic and superoleophilic coating mesh has been reported by Jiang et al. 8 Along this line, more recently, the creation of nanometre-or micrometre-sized porous materials with excellent surface superhydrophobicity has been reported and successfully used for separation and adsorption of oils or organic solvents from water. For example, Yuan et al. reported the selective adsorption of oil from water by a superwetting nanowire membrane. 9 Similar selective adsorption performance has also been reported by Zhang et al. using superhydrophobic nanoporous polydivinylbenzene. 10 Due to their excellent selective adsorption performance, fast adsorption kinetics, good working capacity and recyclable use performance, these materials have great advantages over those traditional absorbent materials such as active carbons, 11,12 which suffer from a number of drawbacks, including slow adsorption kinetics, poor selectivity and limited working capacity. Owing to the global scale of severe water pollution arising from oil spills and industrial organic pollutants, the creation of efficient absorbent materials for separation and removal of oils or organic pollutants from water should be of great importance to address environmental issues. Broader contextOwing to the global scale of severe water pollution arising from oil spills and industrial organic pollutants, the creation of efficient absorbent materials for separation and removal of oils or organic pollutants from water should be of great importance to address environmental issues. Here we report for the first time the surface superhydrophobicity of the conjugated microporous polymers (CMP) as well as their excellent adsorption performance for oils and organic solvents. Due to their open pore structures and excellent surface superhydrophobicity, oils or non-polar organic solvents can be easily absorbed and separated from water by the CMP without adsorption of water. The CMP also show excellent adsorption performance for those polar organic solvents and toxic organic solvents with the absorbencies ranging approximately from 700 wt% to 1500 wt% for the HCMP-1 and 600 wt% to 2300 wt% for the HCMP-2, respectively. By loading the CMP, the hydrophilic sponge can be changed to be oleophilic to oil. With a loading of 7.0 mg cm À3 of the HCMP-1 ...

a-d) Reproduced with permission. [61] Copyright 2017, Springer Nature. e) Possible OER routes on Zn 0.2 Co 0.8 O 2 with LOM mechanism. [59] Copyright 2019, Springer Nature. f) Scheme representing the proposed OER mechanism on the surface of La 2 LiIrO 6 in acid. Reproduced with permission. [66] Copyright 2016, Nature Publishing Group. g) The mechanism suggested for amorphous iridium oxide and leached perovskites with participation of activated oxygen in the reaction forming oxygen vacancies. Reproduced with permission. [51] Copyright 2018, Springer Nature.

Developing bifunctional efficient electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is in high demand for the development of overall water-splitting devices. In particular, the electrocatalytic performance can be largely improved by designing positive nanoscale-heterojunction with well-tuned interfaces. Herein, a novel top-down strategy is reported to construct the oxide/ sulfide heterostructures (N-NiMoO 4 /NiS 2 nanowires/nanosheets) as a multisite HER/OER catalyst. Starting with the NiMoO 4 nanowires, nitridation in a controlled manner enables activation of Ni sites in NiMoO 4 and then yields oxide/sulfide heterojunction by directly vulcanizing the highly composition-segregated N-NiMoO 4 nanowires. The abundant epitaxial heterogeneous interfaces at atomic-level facilitate the electron transfer from N-NiMoO 4 to NiS 2 , which further cooperate synergistically toward both the hydrogen and oxygen generation in alkali solution. Furthermore, with N-NiMoO 4 /NiS 2 grown carbon fiber cloth as the engineering electrode, the assembled N-NiMoO 4 /NiS 2 -N-NiMoO 4 /NiS 2 system can deliver a current density of 10 mA cm −2 with the cell voltage of 1.60 V in the water-splitting reaction. This current density is 3.39 times higher than that of the Pt-Ir set (2.95 mA cm −2 ). The excellent catalytic performance offered of N-NiMoO 4 /NiS 2 nanowires/nanosheets presents a great example to demonstrate the significance of interface engineering in the field of electrocatalysis.

Neutral aqueous zinc−air batteries (ZABs) are an emerging type of energy devices with substantially elongated lifetime and improved recyclability compared to conventional alkaline ZABs. However, their development is impeded by the lack of robust bifunctional catalyst at the air-electrode for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). Here, we report the controlled synthesis of NiFe 2 O 4 /FeNi 2 S 4 heterostructured nanosheets (HNSs) that are highly efficient in catalyzing OER and ORR, therefore enabling neutral rechargeable ZABs. Associated with the formation of abundant oxide/ sulfide interfaces over NiFe 2 O 4 /FeNi 2 S 4 HNSs' surfaces, the catalyst's oxygen binding energy can be effectively tuned to enhance the OER and ORR activities, as revealed by the density functional theory calculations. In 0.2 M phosphate buffer solution, the optimized NiFe 2 O 4 /FeNi 2 S 4 HNSs present an excellent oxygen electrocatalytic activity and stability, with much lower OER and ORR overpotentials than single-component FeNi 2 S 4 or NiFe 2 O 4 and with negligible performance decay in accelerated durability testing. When used as an air-electrode, the NiFe 2 O 4 /FeNi 2 S 4 HNSs can deliver a power density of 44.4 mW cm −2 and a superior cycling stability (only 0.6% decay after 900 cycles at 0.5 mA cm −2 ), making the resultant ZAB the most efficient and robust one with a neutral aqueous electrolyte reported to date. This work highlights the essential function of the heterostructure interface in oxygen electrocatalysis, opening a new avenue to advanced neutral metal−air batteries.

Electrochemical water splitting to produce hydrogen and oxygen, as an important reaction for renewable energy storage, needs highly efficient and stable catalysts. Herein, FeS /CoS interface nanosheets (NSs) as efficient bifunctional electrocatalysts for overall water splitting are reported. The thickness and interface disordered structure with rich defects of FeS /CoS NSs are confirmed by atomic force microscopy and high-resolution transmission electron microscopy. Furthermore, extended X-ray absorption fine structure spectroscopy clarifies that FeS /CoS NSs with sulfur vacancies, which can further increase electrocatalytic performance. Benefiting from the interface nanosheets' structure with abundant defects, the FeS /CoS NSs show remarkable hydrogen evolution reaction (HER) performance with a low overpotential of 78.2 mV at 10 mA cm and a superior stability for 80 h in 1.0 m KOH, and an overpotential of 302 mV at 100 mA cm for the oxygen evolution reaction (OER). More importantly, the FeS /CoS NSs display excellent performance for overall water splitting with a voltage of 1.47 V to achieve current density of 10 mA cm and maintain the activity for at least 21 h. The present work highlights the importance of engineering interface nanosheets with rich defects based on transition metal dichalcogenides for boosting the HER and OER performance.

The exploration of highly efficient nonprecious metal bifunctional electrocatalysts to boost oxygen evolution reaction and oxygen reduction reaction is critical for development of high energy density metal-air batteries. Herein, a class of CuS/NiS 2 interface nanocrystals (INs) catalysts with atomic-level coupled nanointerface, subtle lattice distortion, and plentiful vacancy defects is reported. The results from temperature-dependent in situ synchrotron-based X-ray absorption fine spectroscopy and electron spin resonance spectroscopy demonstrate that the lattice distortion of 14.7% in CuS/NiS 2 caused by the strong Jahn-Teller effect of Cu, the strong atomic-level coupled interface of CuS and NiS 2 domains, and distinct vacancy defects can provide numerous effective active sites for their excellent bifunctional performance. A liquid Zn-air battery with the CuS/NiS 2 INs as air electrode displays a large peak power density (172.4 mW cm −2 ), a high specific capacity (775 mAh g Zn −1 ), and long cycle life (up to 83 h), making the CuS/NiS 2 INs among the best bifunctional catalysts for Zn-air battery. More remarkably, the flexible CuS/NiS 2 INsbased solid-state Zn-air batteries can power the LED after twisting, making them be promising in portable and wearable electronic devices.

An efficient self‐standing 3D hydrogen evolution cathode has been developed by coating nickel cobaltite (NiCo2O4)/CuS nanowire heterostructures on a carbon fiber paper (CFP). The obtained CFP/NiCo2O4/CuS electrode shows exceptional hydrogen evolution reaction (HER) performance and excellent durability in acidic conditions. Remarkably, as an integrated 3D hydrogen‐evolving cathode operating in acidic electrolytes, CFP/NiCo2O4/CuS maintains its activity more than 50 h and exhibits an onset overpotential of 31.1 mV, an exchange current density of 0.246 mA cm−2, and a Tafel slope of 41 mV dec−1. Compared to other non‐Pt electrocatalysts reported to date, CFP/NiCo2O4/CuS exhibits the highest HER activity and can be used in HER to produce H2 with nearly quantitative faradaic yield in acidic aqueous media with stable activity. Furthermore, by using CFP/NiCo2O4/CuS as a self‐standing electrode in a water electrolyzer, a current density of 18 mA cm−2 can be achieved at a voltage of 1.5 V which can be driven by a single‐cell battery. This strategy provides an effective, durable, and non‐Pt electrode for water splitting and hydrogen generation.

CuS nanocrystals are potential materials for developing low-cost solar energy conversion devices. Understanding the underlying dynamics of photoinduced carriers in CuS nanocrystals is essential to improve their performance in these devices. In this work, we investigated the photoinduced hole dynamics in CuS nanodisks (NDs) using the combination of transient optical (OTA) and X-ray (XTA) absorption spectroscopy. OTA results show that the broad transient absorption in the visible region is attributed to the photoinduced hot and trapped holes. The hole trapping process occurs on a subpicosecond time scale, followed by carrier recombination (∼100 ps). The nature of the hole trapping sites, revealed by XTA, is characteristic of S or organic ligands on the surface of CuS NDs. These results not only suggest the possibility to control the hole dynamics by tuning the surface chemistry of CuS but also represent NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Letters, Vol 6, No. 14 (2015): pg. 2671-2675. DOI. This article is © American Chemical Society and permission has been granted for this version to appear in e-Publications@Marquette. American Chemical Society does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from American Chemical Society. Journal of Physical Chemistry3 the first time observation of hole dynamics in semiconductor nanocrystals using XTA.Keywords: CuS nanodisks; energy conversion; optical transient absorption spectroscopy; X-ray transient absorption spectroscopyCopper sulfides (Cu2-xS), well-known p-type semiconductors due to the stoichiometric deficiency of copper in the lattice, have attracted considerable attention because of their broad applications in diverse fields including photovoltaics, photocatalysis, batteries, chemical sensing, and electronics. [1][2][3][4] There are several stable Cu2-xS phases with the stoichiometric factor x ranging between 0 and 1, from the copperrich chalcocite (Cu2S) to the copper-deficient composition (CuS). Among them, the hexagonal covellite (CuS) is of particular interest due to its significant density of free carriers (holes) in the valence band accounting for its unique metallic conductivity and the strong localized surface plasmon resonance (LSPR) in NIR.5-8 These characteristics, together with its suitable band gap (2.2 eV), make CuS potentially ideal as low-cost light-harvesting and charge-transport materials in photovoltaics and photocatalysis. 7,[9][10][11] The successful utilization of CuS nanocrystals in photocatalysis and photovoltaic devices largely depends on the trapping and relaxation dynamics of charge carriers in CuS nanocrystals. Due to the larger amount of surface states in nanocrystals compared to the bulk materials, the electrons and holes in nanocrystals can be readily trapped at those surface states after photoexcitation, whic...