Charge-Storage Nickel Substrate-Boosted CuP2 Nanosheet for the Electrochemical Oxygen Evolution Reaction.

The electrochemical oxygen evolution reaction (OER) is an essential anodic reaction that converts sustainable energy into chemical fuels, as it can provide protons and electrons. One of the most challenging research directions for the practical application of the OER is the elevation of the activity of noble-metal-free electrocatalysts. Here, we report that the nickel foam can be used as an electron-deficient substrate to tune the surface oxidation state of catalytic electrodes and thus boost the OER activity of CuP2 nanosheets via a charge-storage mechanism. The as-obtained self-standing CuP2/Ni electrodes delivered a current density of 220 mA cm-2 at 370 mV overpotential, which is approximately 5.5 times higher than the benchmarked IrO2 on nickel foam. This work sheds some new light on the design of low-cost electrocatalysts or electrodes with high activity for the electrochemical OER.

Heterojunction-Based Electron Donators to Stabilize and Activate Ultrafine Pt Nanoparticles for Efficient Hydrogen Atom Dissociation and Gas Evolution.

Platinum (Pt) is the most effective bench-marked catalyst for producing renewable and clean hydrogen energy by electrochemical water splitting. There is demand for high HER catalytic activity to achieve efficient utilization and minimize the loading of Pt in catalysts. In this work, we significantly boost the HER mass activity of Pt nanoparticles in Ptx /Co to 8.3 times higher than that of commercial Pt/C by using Co/NC heterojunctions as a heterogeneous version of electron donors. The highly coupled interfaces between Co/NC and Pt metal enrich the electron density of Pt nanoparticles to facilitate the adsorption of H+ , the dissociation of Pt-H bonds and H2 release, giving the lowest HER overpotential of 6.9 mV vs. RHE at 10 mA cm-2 in acid among reported HER electrocatalysts. Given the easy scale-up synthesis due to the stabilization of ultrafine Pt nanoparticles by Co/NC solid ligands, Ptx /Co can even be a promising substitute for commercial Pt/C for practical applications.

Schottky Barrier-Induced Surface Electric Field Boosts Universal Reduction of NOx - in Water to Ammonia.

NOx - reduction acts a pivotal part in sustaining globally balanced nitrogen cycle and restoring ecological environment, ammonia (NH3 ) is an excellent energy carrier and the most valuable product among all the products of NOx - reduction reaction, the selectivity of which is far from satisfaction due to the intrinsic complexity of multiple-electron NOx - -to-NH3 process. Here, we utilize the Schottky barrier-induced surface electric field, by the construction of high density of electron-deficient Ni nanoparticles inside nitrogen-rich carbons, to facilitate the enrichment and fixation of all NOx - anions on the electrode surface, including NO3 - and NO2 - , and thus ensure the final selectivity to NH3 . Both theoretical and experimental results demonstrate that NOx - anions were continuously captured by the electrode with largely enhanced surface electric field, providing excellent Faradaic efficiency of 99 % from both electrocatalytic NO3 - and NO2 - reduction. Remarkably, the NH3 yield rate could reach the maximum of 25.1 mg h-1 cm-2 in electrocatalytic NO2 - reduction reaction, outperforming the maximum in the literature by a factor of 6.3 in neutral solution. With the universality of our electrocatalyst, all sorts of available electrolytes containing NOx - pollutants, including seawater or wastewater, could be directly used for ammonia production in potential through sustainable electrochemical technology.

Electrochemical activation of C-H by electron-deficient W2C nanocrystals for simultaneous alkoxylation and hydrogen evolution.

The activation of C-H bonds is a central challenge in organic chemistry and usually a key step for the retro-synthesis of functional natural products due to the high chemical stability of C-H bonds. Electrochemical methods are a powerful alternative for C-H activation, but this approach usually requires high overpotential and homogeneous mediators. Here, we design electron-deficient W2C nanocrystal-based electrodes to boost the heterogeneous activation of C-H bonds under mild conditions via an additive-free, purely heterogeneous electrocatalytic strategy. The electron density of W2C nanocrystals is tuned by constructing Schottky heterojunctions with nitrogen-doped carbon support to facilitate the preadsorption and activation of benzylic C-H bonds of ethylbenzene on the W2C surface, enabling a high turnover frequency (18.8 h-1) at a comparably low work potential (2 V versus SCE). The pronounced electron deficiency of the W2C nanocatalysts substantially facilitates the direct deprotonation process to ensure electrode durability without self-oxidation. The efficient oxidation process also boosts the balancing hydrogen production from as-formed protons on the cathode by a factor of 10 compared to an inert reference electrode. The whole process meets the requirements of atomic economy and electric energy utilization in terms of sustainable chemical synthesis.

Electrochemical Reduction of N2 into NH3 by Donor-Acceptor Couples of Ni and Au Nanoparticles with a 67.8% Faradaic Efficiency.

The traditional NH3 production method (Haber-Bosch process) is currently complemented by electrochemical synthesis at ambient conditions, but the rather low selectivity (as indicated by the Faradaic efficiency) for the electrochemical reduction of molecular N2 into NH3 impedes the progress. Here, we present a powerful method to significantly boost the Faradaic efficiency of Au electrocatalysts to 67.8% for the nitrogen reduction reaction (NRR) by increasing their electron density through the construction of inorganic donor-acceptor couples of Ni and Au nanoparticles. The unique role of the electron-rich Au centers in facilitating the fixation and activation of N2 was also investigated via theoretical simulation methods and then confirmed by experimental results. The highly coupled Au and Ni nanoparticles supported on nitrogen-doped carbon are stable for reuse and long-term performance of the NRR, making the electrochemical process more sustainable for practical application.

Boosting selective nitrogen reduction to ammonia on electron-deficient copper nanoparticles.

Production of ammonia is currently realized by the Haber-Bosch process, while electrochemical N2 fixation under ambient conditions is recognized as a promising green substitution in the near future. A lack of efficient electrocatalysts remains the primary hurdle for the initiation of potential electrocatalytic synthesis of ammonia. For cheaper metals, such as copper, limited progress has been made to date. In this work, we boost the N2 reduction reaction catalytic activity of Cu nanoparticles, which originally exhibited negligible N2 reduction reaction activity, via a local electron depletion effect. The electron-deficient Cu nanoparticles are brought in a Schottky rectifying contact with a polyimide support which retards the hydrogen evolution reaction process in basic electrolytes and facilitates the electrochemical N2 reduction reaction process under ambient aqueous conditions. This strategy of inducing electron deficiency provides new insight into the rational design of inexpensive N2 reduction reaction catalysts with high selectivity and activity.

Nitrogen-thermal modification of the bifunctional interfaces of transition metal/carbon dyads for the reversible hydrogenation and dehydrogenation of heteroarenes.

A nitrogen-thermal approach via the reaction between transition metal species and N dopants affords us the ability to optimize the tradeoff between the number of exposed transition metal/carbon (exemplified by cobalt in this work) boundaries and the most pronounced interfacial rectifying contact to achieve the highly efficient and selective hydrogenation and dehydrogenation of N-heterocycle compounds in a reversible manner.

Schottky Barrier Induced Coupled Interface of Electron-Rich N-Doped Carbon and Electron-Deficient Cu: In-Built Lewis Acid-Base Pairs for Highly Efficient CO2 Fixation.

Highly efficient fixation of CO2 for the synthesis of useful organic carbonates has drawn much attention. The design of sustainable Lewis acid-base pairs, which has mainly relied on expensive organic ligands, is the key challenge in the activation of the substrate and CO2 molecule. Here, we report the application of Mott-Schottky type nanohybrids composed of electron-deficient Cu and electron-rich N-doped carbon for CO2 fixation. A ligand-free and additive-free method was used to boost the basicity of the carbon supports and the acidity of Cu by increasing the Schottky barrier at their boundary, mimicking the beneficial function of organic ligands acting as the Lewis acid and base in metal-organic frameworks (MOFs) or polymers and simultaneously avoiding the possible deactivation associated with the necessary stability of a heterogeneous catalyst. The optimal Cu/NC-0.5 catalyst exhibited a remarkably high turnover frequency (TOF) value of 615 h-1 at 80 °C, which is 10 times higher than that of the state-of-the-art metal-based heterogeneous catalysts in the literature.

A Polyimide Nanolayer as a Metal-Free and Durable Organic Electrode Toward Highly Efficient Oxygen Evolution.

The exploitation of metal-free organic polymers as electrodes for water splitting reactions is limited by their presumably low activity and poor stability, especially for the oxygen evolution reaction (OER) under more critical conditions. Now, the thickness of a cheap and robust polymer, poly(p-phenylene pyromellitimide) (PPPI) was rationally engineered by an in situ polymerization method to make the metal-free polymer available for the first time as flexible, tailorable, efficient, and ultra-stable electrodes for water oxidation over a wide pH range. The PPPI electrode with an optimized thickness of about 200 nm provided a current density of 32.8 mA cm-2 at an overpotential of 510 mV in 0.1 mol L-1 KOH, which is even higher than that (31.5 mA cm-2 ) of commercial IrO2 OER catalyst. The PPPI electrodes are scalable and stable, maintaining 92 % of its activity after a 48-h chronoamperometric stability test.

Tuning the Adsorption Energy of Methanol Molecules Along Ni-N-Doped Carbon Phase Boundaries by the Mott-Schottky Effect for Gas-Phase Methanol Dehydrogenation.

Engineering the adsorption of molecules on active sites is an integral and challenging part for the design of highly efficient transition-metal-based catalysts for methanol dehydrogenation. A Mott-Schottky catalyst composed of Ni nanoparticles and tailorable nitrogen-doped carbon-foam (Ni/NCF) and thus tunable adsorption energy is presented for highly efficient and selective dehydrogenation of gas-phase methanol to hydrogen and CO even under relatively high weight hourly space velocities (WHSV). Both theoretical and experimental results reveal the key role of the rectifying contact at the Ni/NCF boundaries in tailoring the electron density of Ni species and enhancing the absorption energies of methanol molecules, which leads to a remarkably high turnover frequency (TOF) value (356 mol methanol mol-1 Ni h-1 at 350 °C), outpacing previously reported bench-marked transition-metal catalysts 10-fold.

An electrochemical glutathione biosensor: ubiquinone as a transducer.

In this paper, coenzyme Q10 (Ubiquinone, CoQ10) was used for the first time as a transducer to construct electrochemical biosensor for effectively detecting γ-L-glutamyl-L-cysteinyl-glycine (glutathione, GSH). CoQ10 modified electrode was fabricated by attaching its gel mixed with multi-walled carbon nanotubes (MWNTs)/ionic liquid (IL). In the optimum conditions, based on the increasing of reduction peak current of CoQ10 caused by GSH through voltammetric technology, it was found that the peak current of CoQ10 was linear with the concentration of GSH in the range from 4.0×10(-9) to 2.0×10(-7)mol L(-1) at the pH 7.00, and the limit of detection was 3.2×10(-10)mol L(-1) (S/N=3). The results revealed that this method could be used to determine GSH in actual blood samples with the superiority of excellent selectivity, high stability and sensitivity. The strategy explored here might provide a new pathway to design novel multi-function transducers for detecting GSH, which has unique characteristic and potential application in the fields of sensor and medical diagnosis.