The successful isolation of metal phthalocyanines into graphene-supported microporous polyanilines results in rich exposure to active sites, rapid electron transfer and efficient gas transport channels, which synergically enhance NH3 sensing.

Although the activity of electrocatalysts towards oxygen evolution reaction (OER) has achieved considerable improvement by modulating the intrinsic electron structure, the role of supports to OER performance, often being reduced to enhancing the conductivity, is not fully explored. In this paper, a proof-of-concept study based on a series of hybrids of nickel iron (hydr)oxide nanoparticles (NiFeO NPs) and carbon supports with different oxidation level compared the motivation of supports for OER activity. The key to implementation lay in anchoring and growing of NiFeO NPs on the various carbon supports by electrostatic assembly and subsequent in-situ reduction. A series of experiments indicated that the strong coupling of metal ions and graphene oxide (GO) contributed to the formation of ultrasmall NiFeO NPs (approximate to 2 nm) and the firm interaction between NiFeO NPs and GO, which in turn resulted in exposing more metal atoms, modulating local electron structure of active sites, and accelerating the charge-transfer ability. The OER activity of optimal NiFeO NPs anchored on rGO (NiFeO NPs/rGO) was significantly elevated, achieving an overpotential as small as 201 mV at 10 mA cm(-2) and a low Tafel slope of 68 mV dec(-1), as well as remarkable stability. Such exciting capacity for catalyzing OER prevailed over the vast majority of previously reported transition-metal electrocatalysts, even superior to numerous noble metal-containing catalysts. The electrolyzer employing NiFeO NPs/rGO and commercial Pt/C for anode and cathode could be powered by a solar cell for efficient alkaline seawater splitting. This work opens up a universal and scalable way for further advancing the intrinsic activity of energy-related materials.

Nanostructure engineering of heteroatom-doped carbon catalysts can greatly enhance their electrocatalytic activity by increasing the accessible active sites and beneficial physical properties (e.g., surface area, conductivity, etc.). Herein, we successfully constructed ultra-thin N,P co-doped carbon (NPC) on the surface of multi-walled carbon nanotubes (CNT) by using phytic acid (PA) as a "guide". The rich phosphate groups in PA allow them to be covalently modified on the surface of CNT by the condensation reaction and to further attract large aniline monomers through acid-base interactions, resulting in the uniform and tight bonding between polyaniline and CNT after the polymerization process. During the subsequent thermal reaction, PA also serves as a self-sacrificial dopant for the formation of ultra-thin NPC and the doping amount of P in NPC can be easily adjusted by changing the amount of PA. Due to the abundance of active sites, large electrochemically active surface area and rapid electron transfer, the developed CNT@NPC presents remarkable electrocatalytic activities for the hydrogen evolution reaction (HER) with an overpotential of 167, 440 and 304 mV to reach a current density of 10 mA cm-2 in acidic, neutral, and alkaline electrolytes, respectively. In particular, its acidic HER activity exceeds that of most reported metal-free electrocatalysts and is comparable to that of some excellent transition metal-based catalysts. The approach proposed here is of potential importance for the preparation of ideal heteroatom-doped carbon/nanocarbon composites for use in a variety of future energy conversion systems.

AbstractEven though transition‐metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)‐modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B‐CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm−2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics.

The doping amount of heteroatoms in N, S co-doped carbon nanotubes (CNT-NS) was accurately and extensively regulated by retarding pyrolysis-gas diffusion. The effect of the content of N and S on the hydrogen evolution activity of CNT-NS was revealed for the first time both experimentally and theoretically.

Modulating the allocation of nitrogen and phosphorus in graphene by a judiciously designed supramolecular architecture achieved a record-low overpotential in nonmetallic doped graphene for the HER.

Energy-saving electrolytic hydrogen production is the precondition for implementing large-scale hydrogen energy exploitation. Replacing the sluggish water oxidation reaction with thermodynamically more favorable pollutant electro-oxidation (degradation) is a very promising approach to combine energy-efficient hydrogen production and sewage treatment. Herein, a homologous asymmetrical two-electrode configuration, made up of self-assembly induced mosslike Fe2O3 and FeP on electro-oxidized carbon paper (ECP), was used to electrolyze the integrated hydrazine oxidation-hydrogen evolution system. The free-standing Fe2O3/ECP electrode was fabricated by pyrolyzing iron phthalocyanine/ECP self-assembly in air and serves as an anodic reaction catalyst. Subsequent phosphidation of the Fe2O3/ECP leads to the formation of the FeP/ECP catalyst for hydrogen evolution reaction. The cross-linked mosslike Fe2O3 and FeP nanoparticles densely covered on the surface of ECP provide richly exposed catalytic sites and the well-distributed stacking holes among nanoparticles offer the expedited electrolyte/gas transmission path. Coupled with hydrazine oxidation, the Fe2O3/ECP parallel to FeP/ECP configuration presents a superior cell voltage of only 0.93 Vat 10 mA cm(-2) for synchronous hydrogen production, which is substantially lower than that of traditional overall water splitting system. Besides the low-voltage-driven energy efficiency, the catalyst electrodes also afford excellent run-to-run reproducibility and stability, as well as good batch-to-batch repeatability. Such a win-win coupling strategy offers the prospect of synchronously achieving energy-saving hydrogen production and the green conversion (or degradation) of hydrazine in wastewater.