Herein, we compare the bulk, 2H and 3R phases of two most prevalent TMD materials: MoS and WS. The 3R phase outperforms its 2H phase counterpart in hydrogen evolution reaction catalysis and is even comparable with the exfoliated, 1T phase in the case of MoS.

This work provides a first insight into the inherent electrochemistry and catalytic activities of group 4 transition metal dichalcogenides.

In the last few years, the development of versatile coating chemistries has become a hot topic in surface science after the discovery that catecholamines can lead to conformal coatings upon oxidation from aqueous solutions. Recently, it was found that aminomalononitrile (AMN), a molecule implicated in the appearance of life on earth, is an excellent prototype of novel material-independent surface functionalizing agents leading to conformal and biocompatible coatings in a simple and direct chemical process from aqueous solutions. So far, very little insight has been gained regarding the mechanisms underlying coating deposition. In this paper we show that the chemical evolution of AMN film deposition under slightly basic conditions is different in solution and on silica. Thereon, the coating proceeds via a nucleation process followed by further deposition of islands which evolve to produce nitrogen-rich superhydrophilic fibrillar structures. Additionally, we show that AMNbased material can form films at the air-solution interface from unshaken solutions. These 2 results open new vistas into the chemistry of HCN-derived species of potential relevance in materials science.

The development of electrocatalysts is crucial for renewable energy applications. Metal-doped graphene hybrid materials have been explored for this purpose, however, with much focus on noble metals, which are limited by their low availability and high costs. Transition metals may serve as promising alternatives. Here, transition metal-doped graphene hybrids were synthesized by a simple and scalable method. Metal-doped graphite oxide precursors were thermally exfoliated in either hydrogen or nitrogen atmosphere; by changing exfoliation atmospheres from inert to reductive, we produced materials with different degrees of oxidation. Effects of the presence of metal nanoparticles and exfoliation atmosphere on the morphology and electrocatalytic activity of the hybrid materials were investigated using electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. Doping of graphene with transition metal nanoparticles of the 4th period significantly influenced the electrocatalysis of compounds important in energy production and storage applications, with hybrid materials exfoliated in nitrogen atmosphere displaying superior performance over those exfoliated in hydrogen atmosphere. Moreover, nickel-doped graphene hybrids displayed outstanding electrocatalytic activities towards reduction of O2 when compared to bare graphenes. These findings may be exploited in the research field of renewable energy.

It is crucial to develop electrocatalysts for the oxygen reduction reaction (ORR) for renewable energy applications. Mixed‐valence transition‐metal oxides with a spinel structure have been explored for this purpose. In this work, we study the influence of the composition of the catalysts (XY2O4, X=Ni, Zn and Y=Co, Mn) on the ORR. The four different types of spinel oxide nanocrystals (NiCo2O4, NiMn2O4, ZnCo2O4, and ZnMn2O4) were synthesized by a simple and scalable method. This allowed for a systematic investigation of the transition‐metal influence on the performance of the ORR. Given the general spinel structure of XY2O4, we systematically changed X (Ni, Zn) and Y (Co, Mn). The effects of the presence of different metals in the spinel oxide on the morphology and electrocatalytic properties of the materials toward the ORR were investigated and compared by using scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron microscopy, and voltammetry. In general, cobalt‐based spinel oxides displayed a significant electrocatalytic activity towards the ORR, with Ni‐substituted spinel oxides outperforming their respective Zn‐substituted congeners. These findings may have great impact in the research field of renewable energy.

Metallic 1T‐phase transition metal dichalcogenides have been recognized for their desirable properties like high surface‐to‐volume ratio, high conductivity, and capacitive behavior, making them outstanding for catalytic and sensing applications. Herein, a hydrogen peroxide (H2O2) biosensor is constructed by the immobilization of hemoglobin (Hb) on 1T‐phase WS2 (1T‐WS2) sheets, and entrapment by glutaraldehyde. 1T‐WS2 not only displays electrocatalytic activity toward the reduction of H2O2 but also provides a high surface‐to‐volume ratio and conductive platform for the immobilization of Hb and facilitation of its electron transfer to the electrode surface. The advantageous role of 1T‐phase WS2 is further demonstrated for the construction of a heme‐based H2O2 biosensor compared to its 1T‐phase MoS2, MoSe2, and WSe2 counterparts. Synergistic interactions between 1T‐WS2 and Hb result in a H2O2 biosensor with high analytical performance in terms of wide range, sensitivity, selectivity, reproducibility, repeatability, and stability. These findings have profound impact in the research fields of electrochemical sensing and biodiagnostics.

The electrochemical behavior of iron ion in haemoglobin provides insight to the chemical activity in the red blood cell which is important in the field of hematology. Herein, the detection of haemoglobin in human red blood cells on glassy carbon electrode (GC) was demonstrated. Red blood cells or raw blood cells was immobilized on a glassy carbon electrode surface with Nafion films employed to sandwich the layer of biological sample firmly on the electrode surface. Cyclic voltammetry (CV) analyses revealed a well-defined reduction peak for haemoglobin at about −0.30 V (vs. Ag/AgCl) at the red blood cell (GC-Nf-RBC-3Nf) and blood (GC-Nf-B-3Nf) film modified GCE in a pH 3.5 phosphate buffer solution. We further demonstrated that the complex biological conditions of a human red blood cell displayed no interference with the detection of haemoglobin. Such findings shall have an implication on the possibilities of studying the electrochemical behaviour of haemoglobin directly from human blood, for various scientific and clinical purposes.

Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy.