Construction of a nano dispersed Cr/Fe-polycrystalline sensor via high-energy mechanochemistry for simultaneous electrochemical determination of dopamine and uric acid

A bimetallic polycrystalline sensor (Cr/Fe-SNCM) having nanosized and high dispersion was designed and used for the electrochemical simultaneous determination of dopamine (DA) and uric acid (UA). Catalytic nanosized Cr/Fe were highly anchored on N/S/O-contained porous carbon with high dispersion and polycrystalline Cr/Fe via energetic mechanochemical method and high-temperature carbonization. The obtained Cr/Fe-SNCM exhibited high graphitized carbon supporter and endowed high electron transport and signal output for the whole sensor. Moreover, highly dispersed Cr/Fe sites and the polycrystalline form (metal-N/S/O) efficiently enhanced the catalytic reaction, leading to a limits of detection (based on the 3σ/m criterion) of 25.8 and 22.5 nM for DA and UA, respectively. This is 1-2 orders of magnitude lower than many state-of-the-art reported sensors. The Cr/Fe-SNCM_1.0 sensor exhibited wide working range (0.1 to 10.0 μM), high recovery (96-103%) and low relative standard deviation (RSD = 3.2-4.7%) for DA and UA in real serum samples, possessing high significance for practical large-scale applications.

Characterization of the nitrogen state in HPHT diamonds grown in an Fe–C melt with a low sulfur addition

This paper reports the results of high-pressure high-temperature (HPHT) diamonds growing in an Fe–C melt with introduction of 1 wt% sulfur.

Importance of Interfacial Structures in the Catalytic Effect of Transition Metals on Diamond Growth

Here, using ab initio calculations, we investigated the interaction between transition metals (M) and diamond C(111) surfaces. As a physical parameter describing the catalytic effect of a transition metal on diamond growth, we considered interfacial energy difference, ΔE int, between 1 × 1 and 2 × 1 models of M/C(111). The results showed that the transition-metal elements in the middle of the periodic table (groups 4-10) favor a 1 × 1 M/C(111) structure with diamond bulk-like interfaces, while the elements at the sides of the periodic table (groups 3, 11, and 12) favor a 2 × 1 M/C(111) structure with the 2 × 1 Pandey chain structure of C(111) underneath M. In addition, calculations of MC carbide formation for early transition metals (groups 3-6) showed that they have a tendency to form MC rather than M/C(111), which explains their low efficiency as catalysts for diamond growth. Further analysis suggests that ΔE int could serve as another parameter (catalytic descriptor) for describing catalytic diamond growth in addition to the conventional parameter of the melting temperature of M.

Effect of Ni2O3 on diamond crystal growth in an Fe–Ni–C system under high temperature and high pressure

In this paper, the oxygen-containing diamond large single crystals were successfully synthesized by adding Ni₂O₃ to the Fe–Ni–C system under HPHT. The oxygen affects the P–T conditions for diamond synthesis, and morphology of diamond.

The effect of pressure on synthetic diamond crystals at high temperatures and pressures in an Fe/Ni catalyst system

Pressure is a necessary condition for the growth of natural diamond.

Growth and characterization of diamond single crystals grown in the Fe–S–C system by the temperature gradient method

Diagram of the apparatus for the HPHT diamond synthesis: (a) alloy hammer + pyrophyllite assembly block; (b) sample assembly.

The characteristics of Ib diamond crystals synthesized in a Fe–Ni–C system with different SiC contents

The influence of different SiC doping contents on the synthesis of diamond crystals in the Fe–Ni–C system was investigated.

Study on the crack phenomenon of heavy FeS-doped Ib diamond crystals with {111} surface as growth surface in Fe–Ni–C system

Herein, the characteristics of heavy FeS-doped diamond crystals were studied using a China-type large volume cubic high-pressure apparatus (CHPA) with FeNi alloy as the catalyst at 6.0–6.5 GPa and 1350–1400 °C.

Effect of sulfur on diamond growth and morphology in metal–carbon systems

Sulfur additives inhibit diamond crystallization in the Fe–Ni–C system at 6 GPa and 1400 °C and affect the diamond crystal morphology and nitrogen impurity content.

Study on the characteristics of Ib diamond crystals synthesized with Fe3O4 doped in an Fe–Ni–C system

Fe₃O₄ is a common earth mineral, which often exists in the form of inclusions in natural diamond.