Hangjia Shen

Iron-N–C (Fe–N–C) materials are facilely synthesized by chemical vapor deposition (CVD) and applied in detecting hydrogen peroxide. Benefiting from the merits of Fe–N–C configuration, the achieved Fe–N–C modified electrodes exhibit outstanding electrochemical sensing performances toward pH-universal hydrogen peroxide detection.

Metal phosphides with high electronic conductivity are recognized as promising electrocatalyst for oxygen reduction reaction (ORR). Herein, we report a family of cobalt phosphides (CoP, CoP ₂ , and CoP/CoP ₂ ) encapsulated in thin carbon layer as two-electron (2e ^- ) ORR electrocatalysts for H ₂ O ₂ production. Benefiting from the regulation of cobalt phosphide, CoP/CoP ₂ @NPC exhibited the highest H ₂ O ₂ yield among the three types of cobalt phosphides studied, with a high H ₂ O ₂ selectivity (>90%) over a potential ranging from 0.2 to 0.7 V vs the reversible hydrogen electrode. Continuous generation of H ₂ O ₂ is achieved at an outstanding rate of 1.93 mol g cat . − 1 h − 1 with a Faraday efficiency of 83%.

Transition metal sulfide (TMS) promises an excellent prospect in electrocatalysis with high intrinsic activity but poor conductivity. In this work, a series of TMS wrapped by a thin carbon layer with enhanced conductivity have been developed by a facile and rapid strategy. Among them, the prepared CoS_x compound exhibits the optimal ORR and OER performances because of the synergistic effect between the high intrinsic activity of CoS_x and the desirable conductivity of carbon layer. More importantly, the CoS_x‐based zinc‐air batteries (ZABs) exhibit a current density of 10 mA cm⁻² with voltage gap of 0.8 V and remarkable cycling durability, which is comparable to those of the state‐of‐art noble Pt/C+IrO₂ batteries. Therefore, this work introduces a facile route that opens up a new horizon and inspiration for the development of sulfide for energy conversion.

Oxygen electroreduction (ORR) via a two-electron pathway is a promising alternative for hydrogen peroxide (H₂O₂) synthesis in small-scale applications. In this work, nitrogen and sulfur co-doped carbon coated zinc sulfide nanoparticles (ZnS@C) are synthesized using facile high-temperature annealing. In an alkaline electrolyte, the presence of ZnS suppresses the reduction of H₂O₂ during the ORR and contributes to high H₂O₂ selectivity (∼90%) over a wide potential range (0.40–0.80 V). Continuous generation of H₂O₂ is in turn achieved at an outstanding rate of 1.485 mol g_cat. ⁻¹ h⁻¹ with a faradaic efficiency of 93.7%.

The coordination environments of iron (Fe) in Fe–N–C catalysts determine their intrinsic activities toward oxygen reduction reactions (ORR). The precise atomic-level regulation of the local coordination environments is thus of critical importance yet quite challenging to achieve. Here, atomically dispersed Fe–N–C catalyst with O–Fe–N₂C₂ moieties is thoroughly studied for ORR catalysis. Advanced synchrotron X-ray characterizations, along with theoretical modeling, explicitly unraveled the penta-coordinated nature of the Fe center in the catalytic domain and the energetically optimized ORR pathways on the well-tailored O–Fe–N₂C₂ moieties. The combined structure identification from both experiments and theory provides an opportunity to understand the role of the coordination environments in directing the catalytic activity of single-atom or single-site catalysts; not only the center metal atom but also the whole coordinating atoms participate in the catalytic cycle.

A bifunctional material which has high performance towards overall water splitting in alkaline media is developed by coupling FeNi₃N and FeNi₃ in nanoscale.

Both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for metal-air batteries. Achieving a single phase that offers both functionalities is of practical relevance. Here, we report a facile method to couple Fe-N _x moieties and FeNi ₃ nanoparticles, and embed these in nitrogen-doped carbon nanotubes (Fe/FeNi ₃ @NC). The Fe/FeNi ₃ @NC catalyst demonstrates excellent bifunctional performance in 0.10 molar potassium hydroxide. We observe a half-wave potential of 0.83 V for ORR, and a potential of 1.58 V at a current density of 10 mA cm ⁻² for OER. The oxygen electrode fabricated using Fe/FeNi ₃ @NC exhibits a peak power density of 143 mW cm ⁻² for rechargeable Zn-air battery. Over a ∼9 h duration test, the material is also shown to be as stable as the commercial Pt/C + IrO ₂ in operating conditions.