Correlations between the rate of the hydrogen electrode reaction and the properties of alloys

Highly efficient and robust noble-metal free bifunctional water electrolysis catalyst achieved via complementary charge transfer

The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure. Herein, multidirectional charge transfer concept has been adopted within heterostructured catalysts to develop an efficient and robust bifunctional water electrolysis catalyst, which comprises perovskite oxides (La_0.5Sr_0.5CoO_3–δ, LSC) and potassium ion-bonded MoSe₂ (K-MoSe₂). The complementary charge transfer from LSC and K to MoSe₂ endows MoSe₂ with the electron-rich surface and increased electrical conductivity, which improves the hydrogen evolution reaction (HER) kinetics. Excellent oxygen evolution reaction (OER) kinetics of LSC/K-MoSe₂ is also achieved, surpassing that of the noble metal (IrO₂), attributed to the enhanced adsorption capability of surface-based oxygen intermediates of the heterostructure. Consequently, the water electrolysis efficiency of LSC/K-MoSe₂ exceeds the performance of the state-of-the-art Pt/C||IrO₂ couple. Furthermore, LSC/K-MoSe₂ exhibits remarkable chronopotentiometric stability over 2,500 h under a high current density of 100 mA cm⁻².

While water electrolysis offers a renewable means to obtain H₂, it is necessary to understand the roles adopted by catalytic components. Here, authors explore a heterostructured MoSe₂/perovskite oxide catalyst that shows multidirectional charge transfer to boost electrocatalytic water splitting.

Ultrasensitive simultaneous voltammetric determination of 4-aminophenol and acetaminophen based on bimetallic MOF-derived nitrogen-doped carbon coated CoNi alloy

Simultaneous electrochemical determination of 4-aminophenol (4-AP) and acetaminophen (ACOP) is crucial due to their high toxicity when are overused. Herein, a novel electrocatalyst of nitrogen-doped carbon coated CoNi alloy (CoNi@CN) is derived from bimetallic CoNi(BDC)₂(DABCO) for the first time. A series of characterizations demonstrate that composite has been successfully synthesized, and all elements are evenly distributed in the catalyst. The optimal sensor based on Co₁Ni₁@CN-700 exhibits two wide linear responses for 4-AP (0.05-60 μM and 60-250 μM) and ACOP (0.05-40 μM and 40-150 μM) with the lowest detection limit of 5.2 nM and 3.8 nM compared with current known reports. Moreover, the sensor has superior reproducibility, selectivity and stability. In addition, the wonderful recoveries also are obtained when sensor is used to detect 4-AP and ACOP in real samples, illustrating that electrochemical sensor has great prospect in the clinical application.

In-situ local phase-transitioned MoSe2 in La0.5Sr0.5CoO3-δ heterostructure and stable overall water electrolysis over 1000 hours

Developing efficient bifunctional catalysts for overall water splitting that are earth-abundant, cost-effective, and durable is of considerable importance from the practical perspective to mitigate the issues associated with precious metal-based catalysts. Herein, we introduce a heterostructure comprising perovskite oxides (La_0.5Sr_0.5CoO_3–δ) and molybdenum diselenide (MoSe₂) as an electrochemical catalyst for overall water electrolysis. Interestingly, formation of the heterostructure of La_0.5Sr_0.5CoO_3–δ and MoSe₂ induces a local phase transition in MoSe₂, 2 H to 1 T phase, and more electrophilic La_0.5Sr_0.5CoO_3–δ with partial oxidation of the Co cation owing to electron transfer from Co to Mo. Together with these synergistic effects, the electrochemical activities are significantly improved for both hydrogen and oxygen evolution reactions. In the overall water splitting operation, the heterostructure showed excellent stability at the high current density of 100 mA cm⁻² over 1,000 h, which is exceptionally better than the stability of the state-of-the-art platinum and iridium oxide couple.

While catalysts are necessary for H₂ and O₂ production from water, developing materials capable of evolving both under the same conditions has proven challenging. Here, authors prepare perovskite-oxide and molybdenum sulfide heterostructures as bifunctional water-splitting electrocatalysts.