Efficient and low-cost electrocatalysts for the oxygen evolution reaction are essential components of renewable energy technologies, such as solar fuel synthesis and providing a hydrogen source for powering fuel cells. Here we report that the nitrogen-doped carbon materials function as the efficient oxygen evolution electrocatalysts. In alkaline media, the material generated a current density of 10 mA cm À 2 at the overpotential of 0.38 V, values that are comparable to those of iridium and cobalt oxide catalysts and are the best among the non-metal oxygen evolution electrocatalyst. The electrochemical and physical studies indicate that the high oxygen evolution activity of the nitrogen/carbon materials is from the pyridinic-nitrogen-or/and quaternary-nitrogen-related active sites. Our findings suggest that the non-metal catalysts will be a potential alternative to the use of transition metal-based oxygen evolution catalysts.

Many biomolecules are chiral--they can exist in one of two enantiomeric forms that only differ in that their structures are mirror images of each other. Because only one enantiomer tends to be physiologically active while the other is inactive or even toxic, drug compounds are increasingly produced in an enantiomerically pure form using solution-phase homogeneous catalysts and enzymes. Chiral surfaces offer the possibility of developing heterogeneous enantioselective catalysts that can more readily be separated from the products and reused. In addition, such surfaces might serve as electrochemical sensors for chiral molecules. To date, chiral surfaces have been obtained by adsorbing chiral molecules or slicing single crystals so that they exhibit high-index faces, and some of these surfaces act as enantioselective heterogeneous catalysts. Here we show that chiral surfaces can also be produced through electrodeposition, a relatively simple solution-based process that resembles biomineralization in that organic molecules adsorbed on surfaces have profound effects on the morphology of the inorganic deposits. When electrodepositing a copper oxide film on an achiral gold surface in the presence of tartrate ion in the deposition solution, the chirality of the ion determines the chirality of the deposited film, which in turn determines the film's enantiospecificity during subsequent electrochemical oxidation reactions.

Covalent triazine frameworks, which are crosslinked porous polymers with two-dimensional molecular structures, are promising materials for heterogeneous catalysts. However, the application of the frameworks as electrocatalysts has not been achieved to date because of their poor electrical conductivity. Here we report that platinum-modified covalent triazine frameworks hybridized with conductive carbon nanoparticles are successfully synthesized by introducing carbon nanoparticles during the polymerization process of covalent triazine frameworks. The resulting materials exhibit clear electrocatalytic activity for oxygen reduction reactions in acidic solutions. More interestingly, the platinum-modified covalent triazine frameworks show almost no activity for methanol oxidation, in contrast to commercial carbon-supported platinum. Thus, platinum-modified covalent triazine frameworks hybridized with carbon nanoparticles exhibit selective activity for oxygen reduction reactions even in the presence of high concentrations of methanol, which indicates potential utility as a cathode catalyst in direct methanol fuel cells.

We reported a novel protocol to efficiently synthesize molybdenum carbonitride (MoCN) nanomaterials with dense active sites and high surface area. The key step in this protocol is the preparation of the catalyst precursor, which was obtained by polymerizing diaminopyridine in the presence of hydrogen carbonate. The abundant amino groups in the poly diaminopyridine bound numerous Mo species via coordination bonds, resulting in the formation of dense Mo active sites. The addition of hydrogen carbonate to the synthesis mixture resulted in CO2 gas evolution as the local pH decreased during polymerization. The in situ evolved CO2 bubbles mechanically broke down the precursor into MoCN nanomaterials with a high surface area. The synthesized MoCN materials were demonstrated as an electrocatalyst for hydrogen evolution reaction (HER). It exhibited an HER onset potential of -0.05 V (vs RHE) and a high hydrogen production rate (at -0.14 V vs RHE, -10 mA cm(-2)) and is therefore one of the most efficient, low-cost HER catalysts reported to date.

Nickel-nitrogen-modified graphene (Ni-N-Gr) is fabricated and Ni-N coordination sites on Ni-N-Gr as active centers effectively reduce CO to CO. The faradaic efficiency for CO formation reaches 90% at -0.7 to -0.9 V versus RHE, and the turnover frequency for CO production comes up to ≈2700 h at -0.7 V versus RHE.

The electrochemical oxygen reduction reaction (ORR) is an important cathode reaction of various types of fuel cells. The development of electrocatalysts composed only of abundant elements is a key goal because currently only platinum is a suitable catalyst for ORR. Herein, we synthesized copper-modified covalent triazine frameworks (CTF) hybridized with carbon nanoparticles (Cu-CTF/CPs) as efficient electrocatalysts for the ORR in neutral solutions. The ORR onset potential of the synthesized Cu-CTF/CP was 810 mV versus the reversible hydrogen electrode (RHE; pH 7), the highest reported value at neutral pH for synthetic Cu-based electrocatalysts. Cu-CTF/CP also displayed higher stability than a Cu-based molecular complex at neutral pH during the ORR, a property that was likely as a result of the covalently cross-linked structure of CTF. This work may provide a new platform for the synthesis of durable non-noble-metal electrocatalysts for various target reactions.

Nickel-modified covalent triazine frameworks effectively reduced CO2 to CO because adsorbed COOH was stabilized on the coordinatively-unsaturated Ni atoms in CTF.

The influence of the atomic-level structure of electrode surfaces on electrochemical oscillations has been studied in a system of H2O2 reduction on Pt electrodes in acidic solutions. A current oscillation of another type, named oscillation E, has been found to appear for an atomically flat single-crystal Pt(111) electrode, in addition to previously reported oscillations, named oscillations A and B. Oscillation E does not appear for atomically flat Pt(100), Pt(110), polycrystalline Pt, and Pt(111) with atomically nonflat surfaces. Mathematical simulation by use of a model including an autocatalytic effect of adsorbed OH for dissociative adsorption of H2O2, as a possible explanation, has reproduced the appearance of oscillation E, as well as observed correlations between the appearance of oscillation E and the magnitudes of H2O2-reduction current and “negative” resistance. It is discussed that an efficient autocatalytic mechanism works at the atomically flat Pt(111) surface, which is responsible for the appearance of oscillation E at this surface.