Chao Zhang

Bio: Chao Zhang is an academic researcher from Tianjin University of Technology. The author has contributed to research in topics: Ligand (biochemistry) & Faraday efficiency. The author has an hindex of 4, co-authored 6 publications receiving 41 citations.

Interface Engineering of Partially Phosphidated Co@Co–P@NPCNTs for Highly Enhanced Electrochemical Overall Water Splitting

Abstract: Interface engineering is promising but still challenging for developing highly efficient and stable non-noble-metal-based electrocatalysts for water splitting. Herein, partially phosphidated core@shell Co@Co-P nanoparticles encapsulated in bamboo-like N, P co-doped carbon nanotubes (denoted as Part-Ph Co@Co-P@NPCNTs) are prepared through a pyrolysis-oxidation-phosphidation strategy. In this structure, each Co nanoparticle is covered with a thin Co-P layer to form a special core@shell heterojunction interface, and the core@shell structure is further encapsulated by N, P co-doped CNTs that not only protect the Co from corrosion but also guarantee an effective and fast electron transfer on cobalt phosphide. As a bifunctional catalyst for both the hydrogen evolution reaction and oxygen evolution reaction, it exhibits an excellent activity for overall water splitting, and enables long-term operation without significant degradation. Density functional theory calculations demonstrate that the interface of the Co/Co2 P heterojunction could lower the values of ΔGH * (hydrogen adsorption) and ΔGB (water dissociation), which are negatively correlated to the j10 , because of the electronic structures of up-shifted d-band center. This study not only presents an efficient and stable electrocatalyst for overall water splitting but also provides a special route for the interface engineering of heterostructures.

In-Situ doping-induced crystal form transition of amorphous Pd–P catalyst for robust electrocatalytic hydrodechlorination

Abstract: Developing catalysts with high activity and high atom utilization as well as exploring catalytic active sites are the biggest challenges for the electrocatalytic hydrodechlorination technology. Herein, a novel strategy of Pd crystal transformation induced by in-situ doping was proposed, and a series of amorphous Pd–P nanoparticles (NPs) with controllable coordination environment were synthesized successfully. The amorphous Pd–P NPs catalyst exhibits the highest activity for electrocatalytic hydrodechlorination and good cycling stability when the Pd–P coordination number is 3 and the Pd–Pd coordination number is 4. The 4-chlorophenol hydrodechlorination efficiency of Pd–P-60 NPs reaches 100 % within 2 h, and the mass activity is 8.58 min−1 g−1, which is 5.57 times as high as that for crystalline Pd NPs catalyst. Theoretical calculation shows that Pd–P catalyst facilitates the desorption of phenol and weakens the toxic effect on active sites. Density of states indicate that the doping of P results in a downshift of d-band center, facilitating the desorption of phenol. This work discovers the crystal effect and coordination effect of amorphous Pd–P NPs for electrocatalytic hydrodechlorination, which lays an important theoretical foundation for the design and development of high-performance Pd-based catalysts for electrocatalytic hydrodechlorination.

Sub-Thick Electrodes with Enhanced Transport Kinetics via In Situ Epitaxial Heterogeneous Interfaces for High Areal-Capacity Lithium Ion Batteries.

Abstract: The ever-growing portable electronics and electric vehicle draws the attention of scaling up of energy storage systems with high areal-capacity The concept of thick electrode designs has been used to improve the active mass loading toward achieving high overall energy density However, the poor rate capabilities of electrode material owing to increasing electrode thickness significantly affect the rapid transportation of ionic and electron diffusion kinetics Herein, a new concept named "sub-thick electrodes" is successfully introduced to mitigate the Li-ion storage performance of electrodes This is achieved by using commercial nickel foam (NF) to develop a monolithic 3D with rich in situ heterogeneous interfaces anode (Cu3 P-Ni2 P-NiO, denoted NF-CNNOP) to reinforce the adhesive force of the active materials on NF as well as contribute additional capacity to the electrode The as-prepared NF-CNNOP electrode displays high reversible and rate areal capacities of 681 and 150 mAh cm-2 at 040 and 60 mA cm-2 , respectively The enhanced Li-ion storage capability is attributed to the in situ interfacial engineering within the NiO, Ni2 P, and Cu3 P and the 3D consecutive electron conductive network In addition, cyclic voltammetry, charge-discharge curves, and symmetric cell electrochemical impedance spectroscopy consistently reveal improved pseudocapacitance with enhanced transports kinetics in this sub-thick electrodes

Altering Ligand Fields in Single-Atom Sites through Second-Shell Anion Modulation Boosts the Oxygen Reduction Reaction.

Abstract: Single-atom catalysts based on metal-N4 moieties and anchored on carbon supports (defined as M-N-C) are promising for oxygen reduction reaction (ORR). Among those, M-N-C catalysts with 4d and 5d transition metal (TM4d,5d) centers are much more durable and not susceptible to the undesirable Fenton reaction, especially compared with 3d transition metal based ones. However, the ORR activity of these TM4d,5d-N-C catalysts is still far from satisfactory; thus far, there are few discussions about how to accurately tune the ligand fields of single-atom TM4d,5d sites in order to improve their catalytic properties. Herein, we leverage single-atom Ru-N-C as a model system and report an S-anion coordination strategy to modulate the catalyst's structure and ORR performance. The S anions are identified to bond with N atoms in the second coordination shell of Ru centers, which allows us to manipulate the electronic configuration of central Ru sites. The S-anion-coordinated Ru-N-C catalyst delivers not only promising ORR activity but also outstanding long-term durability, superior to those of commercial Pt/C and most of the near-term single-atom catalysts. DFT calculations reveal that the high ORR activity is attributed to the lower adsorption energy of ORR intermediates at Ru sites. Metal-air batteries using this catalyst in the cathode side also exhibit fast kinetics and excellent stability.

Identification of the Highly Active Co–N4 Coordination Motif for Selective Oxygen Reduction to Hydrogen Peroxide

Abstract: Electrosynthesis of hydrogen peroxide (H2O2) through oxygen reduction reaction (ORR) is an environment-friendly and sustainable route for obtaining a fundamental product in the chemical industry. Co–N4 single-atom catalysts (SAC) have sparkled attention for being highly active in both 2e– ORR, leading to H2O2 and 4e– ORR, in which H2O is the main product. However, there is still a lack of fundamental insights into the structure–function relationship between CoN4 and the ORR mechanism over this family of catalysts. Here, by combining theoretical simulation and experiments, we unveil that pyrrole-type CoN4 (Co–N SACDp) is mainly responsible for the 2e– ORR, while pyridine-type CoN4 catalyzes the 4e– ORR. Indeed, Co–N SACDp exhibits a remarkable H2O2 selectivity of 94% and a superb H2O2 yield of 2032 mg for 90 h in a flow cell, outperforming most reported catalysts in acid media. Theoretical analysis and experimental investigations confirm that Co–N SACDp—with weakening O2/HOO* interaction—boosts the H2O2 production.