Siqi Niu

Bio: Siqi Niu is an academic researcher from Harbin Institute of Technology. The author has contributed to research in topics: Electrocatalyst & Oxygen evolution. The author has an hindex of 8, co-authored 11 publications receiving 293 citations.

Understanding the Phase-Induced Electrocatalytic Oxygen Evolution Reaction Activity on FeOOH Nanostructures

Abstract: The crystalline phase plays a crucial, yet not well-understood, role in enhancing the oxygen evolution reaction (OER) performance of iron oxyhydroxide (FeOOH) materials. Herein, single-phase (α-, β...

How to Reliably Report the Overpotential of an Electrocatalyst

Abstract: The potential was referred to RHE by calibrating the reference electrode with Pt foil (Aldrich) as both the working and the counter electrodes in a sealed standard three-electrode. Saturate the electrolyte with high-purity hydrogen for at least half an hour before performing electrode calibration. Cyclic voltammograms (CV) were performed at the scan rate of 1 mV/s and the average of the two inter-conversion point values was taken to be the thermodynamic potential for the hydrogen evolution reaction. To investigate the influence of temperature on the correction values of the electrodes, a thermostatic water bath was used to precisely control the temperature of the electrolyte at 20, 25 and 30 oC, respectively.

Metal organic framework-derived CoPS/N-doped carbon for efficient electrocatalytic hydrogen evolution

Abstract: Electrocatalytic hydrogen evolution has attracted a great deal of attention due to the urgent need for clean energy. Herein, we demonstrate the synthesis of ternary pyrite-type cobalt phosphosulphide (CoPS) nanoparticles supported on a nitrogen-doped carbon matrix, CoPS/N–C, through carbonization and subsequent phosphosulfurization of Co-based zeolitic imidazolate frameworks (ZIF-67), as promising hydrogen evolution reaction (HER) electrocatalysts in both acidic and alkaline solutions. The polyhedral structure of ZIF-67 can be well maintained in the as-prepared CoPS/N–C nanocomposites. In particular, CoPS/N–C provides a geometric catalytic current density of −10 mA cm−2 at overpotentials of −80 and −148 mV vs. a reversible hydrogen electrode (RHE) and a Tafel slope of 68 and 78 mV dec−1 in 0.5 M H2SO4 and 1 M KOH, respectively, which is superior to most of the transition metal phosphosulfide materials. This MOF-derived synthesis of a transition metal phosphosulfide supported heteroatom-doped carbon matrix provides a promising opportunity for the development of highly efficient electrocatalysts for renewable energy devices.

Low Ru loading RuO2/(Co,Mn)3O4 nanocomposite with modulated electronic structure for efficient oxygen evolution reaction in acid

Abstract: Oxygen evolution reaction (OER) in acidic media usually requires a catalyst with high content of noble Ir or Ru, becoming a bottleneck for the electrochemical water splitting. To address this issue, here we report the fabrication of a RuO2/(Co,Mn)3O4 nanocomposite with low Ru loading (2.51 wt%) as a highly efficient OER catalyst in acidic media (0.5 M H2SO4). Spectroscopic and theoretical studies demonstrate that the introduction of Mn in Co3O4 results in redistribution of electrons and the generation of electron-rich Ru species of the RuO2/(Co,Mn)3O4 catalyst. With modulated electronic properties, the adsorption of O on RuO2/(Co,Mn)3O4 is weakened and the rate determining step, formation of OOH*, of the OER process is therefore accelerated. At such a low Ru loading, RuO2/(Co,Mn)3O4 exhibits superior acidic OER activity (η =270 mV at 10 mA/cm2) and long‐term stability to the benchmark RuO2 catalyst. This work provides a new strategy for the design of cost-effective acidic OER electrocatalysts for energy conversion applications.

Stepwise Electrochemical Construction of FeOOH/Ni(OH)2 on Ni Foam for Enhanced Electrocatalytic Oxygen Evolution

Abstract: As the oxygen evolution reaction (OER) is the bottleneck of electrocatalytic water splitting, it is highly imperative to develop OER catalysts with excellent activity and stability. Herein, we demonstrate a stepwise electrochemical construction of crystalline α-FeOOH/β-Ni(OH)2 composite structure supported on nickel foam (FeOOH/Ni(OH)2/NF) through cathodic electrodeposition of β-Ni(OH)2 nanosheets followed by electrophoretic deposition of α-FeOOH nanoparticles. Taking advantange of the synergistic effect of Ni and Fe as well as the formed interface, this composite structure is highly active for the OER process in alkaline media (1 M KOH), providing a very low overpotential of 207 mV versus the reversible hydrogen electrode (RHE) at a geometric catalytic current density of 40 mA cm–2 and a Tafel slope of 70 mV dec–1, which is superior to most reported (oxy)hydroxide-based OER electrocatalysts. In combination with density functional theory (DFT) calculations, it is verified that the synergistic interface ef...

State of the Art and Prospects in Metal-Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis.

Abstract: Metal-organic framework (MOF) nanoparticles, also called porous coordination polymers, are a major part of nanomaterials science, and their role in catalysis is becoming central. The extraordinary variability and richness of their structures afford engineering synergies between the metal nodes, functional linkers, encapsulated substrates, or nanoparticles for multiple and selective heterogeneous interactions and activations in these MOF-based nanocatalysts. Pyrolysis of MOF-nanoparticle composites forms highly porous N- or P-doped graphitized MOF-derived nanomaterials that are increasingly used as efficient catalysts especially in electro- and photocatalysis. This review first briefly summarizes this background of MOF nanoparticle catalysis and then comprehensively reviews the fast-growing literature reported during the last years. The major parts are catalysis of organic and molecular reactions, electrocatalysis, photocatalysis, and views of prospects. Major challenges of our society are addressed using these well-defined heterogeneous catalysts in the fields of synthesis, energy, and environment. In spite of the many achievements, enormous progress is still necessary to improve our understanding of the processes involved beyond the proof-of-concept, particularly for selective methane oxidation, hydrogen production, water splitting, CO2 reduction to methanol, nitrogen fixation, and water depollution.

Metal–Organic Frameworks in Heterogeneous Catalysis: Recent Progress, New Trends, and Future Perspectives

Abstract: More than 95% (in volume) of all of today’s chemical products are manufactured through catalytic processes, making research into more efficient catalytic materials a thrilling and very dynamic rese...

Metal–organic frameworks as a platform for clean energy applications

Abstract: Metal–organic frameworks (MOFs), an emerging class of porous materials, have shown intriguing and promising properties in a wide range of applications due to their versatile structures, large surface areas, tunable porosity and tailorable chemistry. In recent years one of the most active research fields is to explore energy applications of MOF-based materials. In this review, we present a critical overview on the recent progress of the use of MOF-based materials for gaseous fuel storage, chemical hydrogen storage, solar and electrochemical energy storage and conversion. The challenges and opportunities towards advanced energy technologies with the MOF-based materials are discussed.

Metal-organic framework-derived materials for electrochemical energy applications

Abstract: As emerging crystalline porous organic-inorganic hybrid materials, metal-organic frameworks (MOFs) have been widely used as sacrificial precursors for the synthesis of carbon materials, metal/metal compounds, and their composites with tunable and controllable nanostructures and chemical compositions for electrochemical energy applications. Herein, recent progress of MOF-derived nanomaterials for various electrochemical energy storage and conversion applications including Li-ion batteries, Li-S batteries, Na-ion batteries, supercapacitors, water splitting, and oxygen reduction reaction is reviewed. Structural and compositional design of MOF-derived nanomaterials is systematically summarized, which may hopefully offer inspirations and guidances for future development of MOF-derived nanomaterials for more efficient and more durable electrochemical energy applications.

Metal-organic framework derived Co3O4/MoS2 heterostructure for efficient bifunctional electrocatalysts for oxygen evolution reaction and hydrogen evolution reaction

Abstract: Fabrication of highly efficient, sustainable and low-cost nonprecious metal oxide for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is exceedingly challenging and warranted for overall water splitting. Herein, we synthesized cobalt nanoleaves metal-organic framed work (MOF) on nickel foam substrate with uniform growth. After calcination of Co-MOF, molybdenum disulfide nanosheets is grown by a facial hydrothermal method. The as-prepared heterostructure (Co3O4/MoS2) can act as bifunctional electrocatalysts for overall water splitting. Under optimized condition, synthesized Co3O4/MoS2 heterostructure catalyst exhibited excellent catalytic activity for both OER and HER in 1 M KOH solution with a current density of 20 mA cm−2 at overpotential of 230 mV for OER and 205 mV for HER (@ j = 10 mA cm−2) and Tafel slopes of 45 and 98 mV dec-1, respectively. The superior catalytic activity for both OER and HER arises from the unique heterostructure of Co3O4/MoS2 and the synergistic effects of Co3O4 and MoS2.