We report a facile nitrogenation/exfoliation process to prepare hybrid Ni-C-N nanosheets. These nanosheets are <2 nm thin, chemically stable, and metallically conductive. They serve as a robust catalyst for the hydrogen evolution reaction in 0.5 M HSO, or 1.0 M KOH or 1.0 M PBS (pH = 7). For example, they catalyze the hydrogen evolution reaction in 0.5 M HSO at an onset potential of 34.7 mV, an overpotential of 60.9 mV (at j = 10 mA cm) and with remarkable long-term stability (∼10% current drop after 70 h testing period). They are promising as a non-Pt catalyst for practical hydrogen evolution reaction.

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.

Small molecule probes are indispensable tools to explore diverse cellular events. However, finding a specific probe of a target remains a high challenge. Here we report the discovery of Fast-TRFS, a specific and superfast fluorogenic probe of mammalian thioredoxin reductase, a ubiquitous enzyme involved in regulation of diverse cellular redox signaling pathways. By systematically examining the processes of fluorophore release and reduction of cyclic disulfides/diselenides by the enzyme, structural factors that determine the response rate and specificity of the probe are disclosed. Mechanistic studies reveal that the fluorescence signal is switched on by a simple reduction of the disulfide bond within the probe, which is in stark contrast to the sensing mechanism of published probes. The favorable properties of Fast-TRFS enable development of a high-throughput screening assay to discover inhibitors of thioredoxin reductase by using crude tissue extracts as a source of the enzyme.

Water splitting via the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in producing H2 and O2 is a very important process in the energy field. Developing an efficient catalyst which can be applied to both HER and OER is crucial. Here, a bifunctional catalyst, CFP/NiCo2O4/Co0.57Ni0.43LMOs, has been successfully fabricated. It exhibits remarkable performance for OER in 0.1 M KOH producing a current density of 10 mA cm(-2) at an overpotential of 0.34 V (1.57 V vs. RHE), better than that of the commercial Ir/C (20%) catalyst. Simultaneously, it also exhibits good catalytic performance for HER in 0.5 M H2SO4 producing a current density of 10 mA cm(-2) at an overpotential of 52 mV and a Tafel slope of 34 mV dec(-1), approaching that of the commercial Pt/C (20%) nanocatalyst. Particularly, CFP/NiCo2O4/Co0.57Ni0.43LMOs present better durability under harsh OER and HER cycling conditions than commercial Ir/C and Pt/C. Furthermore, an H-type electrolyzer was fabricated by applying CFP/NiCo2O4/Co0.57Ni0.43LMOs as the cathode and anode electrocatalyst, which can be driven by a single-cell battery. This bifunctional catalyst will be very promising in overall water splitting.