No abstract

No abstract

The commercialization of electrochemical water splitting technology requires electrocatalysts that are cost‐effective, highly efficient, and stable. Herein, an advanced bifunctional electrocatalyst based on single‐atom Co‐decorated MoS2 nanosheets grown on 3D titanium nitride (TiN) nanorod arrays (CoSAs‐MoS2/TiN NRs) has been developed for overall water splitting in pH‐universal electrolytes. When applied as a self‐standing cathodic electrode, the CoSAs‐MoS2/TiN NRs requires overpotentials of 187.5, 131.9, and 203.4 mV to reach a HER current density of 10 mA cm–2 in acidic, alkaline, and neutral conditions, respectively, which are superior to the most previously reported non‐noble metal HER electrocatalysts at the same current density. The CoSAs‐MoS2/TiN NRs anodic electrode also shows low OER overpotentials of 454.9, 340.6, and 508.0 mV, respectively, at a current density of 10 mA cm–2 in acidic, alkaline, and neutral mediums, markedly outperforming current OER catalysts reported elsewhere. More importantly, an electrolyzer delivered from the cathodic and anodic CoSAs‐MoS2/TiN NRs electrodes exhibits an extraordinary overall water splitting performance with good stability and durability in pH‐universal conditions.

In this study, heterogeneous nickel phosphide‐nickel selenide (Ni2P‐NiSe2) nanosheets are constructed to coat zinc phosphide‐based nanorods (ZnP NRs) under a unique core@shell architecture, which acts as a highly active multifunctional catalyst toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The catalyst exhibits an overpotential of 79 mV at 10 mA cm–2 for HER and 326 mV at 100 mA cm–2 for OER in freshwater under an alkaline condition. The formation of an open 3D channel architecture derived from highly conductive ZnP@Ni2P‐NiSe2 nanorods attached nickel foam generates more exposed active sites and promotes fast mass transport. In addition, density functional theory study reveals a synergistic effect between Ni2P and NiSe2 phase to reduce adsorption free energy and increase the electronic conductivity, thereby accelerating the catalytic reaction kinetics. An electrolyzer of the ZnP@Ni2P‐NiSe2(+,‐) requires only cell voltages of 1.54 V (1.43 V) and 1.51 V (1.44 V) to deliver 10 mA cm–2 in freshwater and mimic seawater at 25 °C (75 °C), respectively, along with prospective long‐term stability. Furthermore, the solar energy‐assisted water splitting process demonstrates a solar‐to‐hydrogen efficiency of 19.75%, implying that the catalyst is an effective and low‐cost candidate for water splitting.

The development of hierarchical nanostructures with highly active and durable multifunctional catalysts has a new significance in the context of new energy technologies of water splitting and metal–air batteries. Herein, a strategy is demonstrated to construct a 3D hierarchical oxygenated cobalt molybdenum selenide (O‐Co1−xMoxSe2) series with attractive nanoarchitectures, which are fabricated by a simple and cost‐effective hydrothermal process followed by an exclusive ion‐exchange process. Owing to its highly electroactive sites with numerous nanoporous networks and plentiful oxygen vacancies, the optimal O‐Co0.5Mo0.5Se2 could catalyze the hydrogen evolution reaction and oxygen evolution reaction effectively with a low overpotential of ≈102 and 189 mV, at a current density of 10 mA cm−2, respectively, and exceptional durability. Most importantly, the O‐Co0.5Mo0.5Se2||O‐Co0.5Mo0.5Se2 water splitting device only entails a voltage of ≈1.53 V at a current density of 10 mA cm−2, which is much better than benchmark Pt/C||RuO2 (≈1.56 V). Furthermore, O‐Co0.5Mo0.5Se2 air cathode‐based zinc–air batteries exhibit an excellent power density of 120.28 mW cm−2 and exceptional cycling stability for 60 h, superior to those of state‐of‐art Pt/C+RuO2 pair‐based zinc–air batteries. The present study provides a strategy to design hierarchical 3D oxygenated bimetallic selenide‐based multifunctional catalysts for energy conversion and storage systems.

Atomic metal‐modulated heterostructures have been evidenced as an exciting solution to develop high‐performance multifunctional electrocatalyst toward water splitting. In this research, a catalyst of continuous cobalt‐cobalt oxide (Co‐CoO) lateral heterostructures implanted with well‐dispersed rhodium (Rh) atoms and shelled over conductive porous 1D copper (Cu) nano‐supports for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both freshwater and seawater under alkaline condition is proposed. It is found that synergistic effects coming from uniform Rh atoms at doping level and Co‐CoO heterostructures afford rich multi‐integrated active sites and excellent charge transfer, thereby effectively promoting both HER and OER activities. The material requires overpotentials of 107.3 and 137.7 mV for HER and 277.7 and 260 mV for OER to reach an output of 10 mA cm−1 in freshwater and mimic seawater, respectively, surpassing earlier reported catalysts. Compared to a benchmark a Pt/C//RuO2‐based two‐electrode electrolyzer, a device derived from the 1D‐Cu@Co‐CoO/Rh on copper foam delivers comparable cell voltages of 1.62, 1.60, and 1.70 V at 10 mA cm−2 in freshwater, mimic seawater, and natural seawater, respectively, together with robust stability. These results evidence that 1D‐Cu@Co‐CoO/Rh is a promising catalyst for green hydrogen generation via freshwater and seawater electrolysis applications.

No abstract

A novel sulfur-doped vanadium–molybdenum oxide nanolayer shelling over two-dimensional cobalt nanosheets (2D Co@S-VMoO x NSs) was synthesized via a facile approach. The formation of such a unique 2D core@shell structure together with unusual sulfur doping effect increased the electrochemically active surface area and provided excellent electric conductivity, thereby boosting the activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a result, only low overpotentials of 73 and 274 mV were required to achieve a current response of 10 mA cm–2 toward HER and OER, respectively. Using the 2D Co@S-VMoO x NSs on nickel foam as both cathode and anode electrode, the fabricated electrolyzer showed superior performance with a small cell voltage of 1.55 V at 10 mA cm–2 and excellent stability. These results suggested that the 2D Co@S-VMoO x NSs material might be a potential bifunctional catalyst for green hydrogen production via electrochemical water splitting.