Transition metals are a kind of promising catalysts to apply into electrocatalytic synthesis ammonia by virtue of abundant reserves and low cost. However, many widely used transition metal catalysts usually face the challenge to realize satisfactory catalytic results mainly resulting from the match between catalytic active site and support. Here, a new-type ZnS/NC-X electrocatalyst was reported by in-situ sulfidation of zeolitic imidazolate framework-8 (ZIF-8), where the metal nodes of ZIF-8 reacted with dibenzyl disulfide (BDS) to obtain ZnS nanoparticles and the framework of ZIF-8 was carbonized to form the support. Especially, catalytic active sites (ZnS nanoparticles) and support (NC-X) were adjusted in detailed by changing the ratio of ZIF-8 and BDS. As a result, when the mass ratio of ZIF-8 and BDS was 1:1, the resulted ZnS/NC-2 catalyst achieved a remarkable NH₃ yield of 65.60 μg·h⁻¹·mg⁻¹_cat., Faradaic efficiency (FE) of 18.52% at −0.4 V vs reversible hydrogen electrode (RHE) in 0.05 M H₂SO₄ and catalytic stability, which outperformed most reported transition metal sulfides. The matching catalytic active site and support make our strategy promising for wide catalytic applications.

Heteroatom-doped porous carbon has attracted many researchers’ interests owing to their hierarchical porous and more active sites for nitrogen reduction reaction (NRR). However, the development of simple synthesis strategies to fabricate efficient catalyst is still remaining a challenge. In this work, a series of N, P co-doped porous carbon were prepared by one-step pyrolysis of zeolitic imidazolate framework (ZIF-8) and triphenylphosphine (TPP) under nitrogen atmosphere. The obtained catalyst by calcinating ZIF-8 and TPP with the mass ratio of 1: 5 for three hours was named as PN-C-ZIF-8, which exhibited a high yield rate of ammonia (43.39 μg·h^–1·mg^–1_cat.) and Faraday efficiency (16.67%) in 0.05 M H₂SO₄ at –0.3 V. More importantly, the PN-C-ZIF-8 catalyst had superior selectivity that no hydrazine by-products were detected and long-term durability for 72 h. This study provides an idea for the convenient design and preparation of heteroatom doped carbon materials.

Oxygen evolution reaction (OER) is crucial for hydrogen production as well as other energy storage technologies. CoFe-layered double hydroxide (CoFe-OH) has been widely considered as one of the most efficient electrocatalysts for OER in basic aqueous solution. However, it still suffers from low activity in neutral electrolyte. This paper describes partially oxidized CoFe-OH (PO-CoFe-OH) with enhanced covalency of M-O bonds and displays enhanced OER performance under mild condition. Mechanism studies reveal the suitably enhanced M-O covalency in PO-CoFe-OH shifts the OER mechanism to lattice oxygen oxidation mechanism and also promotes the rate-limiting deprotonation, providing superior OER performance. It just requires the overpotentials of 186 and 365 mV to drive the current density densities of 1 and 10 mA·cm⁻² in 0.1 M KHCO₃ aqueous solution (pH = 8.3), respectively. It provides a new process for rational design of efficient catalysts for water oxidation in mild conditions.

The development of highly efficient and inexpensive catalysts for oxygen evolving reactions (OERs) is extremely urgent for promoting the overall efficiency of water splitting. Herein we report the fabrication of a series of amorphous NiFeB nanoparticles with varying atomic ratios of Fe to (Ni + Fe) (χ_Fe) by a facile chemical-reduction method. The amorphous NiFeB (χ_Fe = 0.20) nanoparticles, combining the merits of in situ formation of borate-enriched NiFeOOH catalytic surface layers, intrinsic amorphous nanostructures, and an optimized degree of Fe doping, displayed highly active electrocatalytic performance towards the OER in a broad range of pH values (from alkaline to neutral conditions). The catalyst exhibited a relatively low overpotential of 216 mV with a Tafel slope of 40 mV/dec on Ni foam and 251 mV with a Tafel slope of 43 mV/dec on glassy carbon at 10 mA/cm² in a 1 M KOH solution, demonstrating much greater OER efficiency than that of commercial RuO₂. Long-term stability testing of the OER performance of NiFeB (χ_Fe = 0.20) by chronoamperometry (overpotential (η) = 320 mV) over 200 h revealed no evidence of degradation. Facile, scalable synthesis and highly active water oxidation make the NiFeB nanoparticles very attractive for OER electrocatalysis.

The design and fabrication of low-cost, high-efficiency, and stable oxygen-evolving catalysts are essential for promoting the overall efficiency of water electrolysis. In this study, mesoporous Ni_1–x Fe _x O _y (0 ≤ x ≤ 1, 1 ≤ y ≤ 1.5) nanorods were synthesized by the facile thermal decomposition of Ni–Fe-based coordination polymers. These polymers passed their nanorod-like morphology to oxides, which served as active catalysts for oxygen evolution reaction (OER). Increasing the Fe-doping amount to 33 at.% decreased the particle size and charge-transfer resistance and increased the surface area, resulting in a reduced overpotential (~302 mV) at 10 mA/cm² and a reduced Tafel slope (~42 mV/dec), which were accompanied by a far improved OER activity compared with those of commercial RuO₂ and IrO₂ electrocatalysts. At Fe-doping concentrations higher than 33 at.%, the trend of the electrocatalytic parameters started to reverse. The shift in the dopant concentration of Fe was further reflected in the structural transformation from a NiO (< 33 at.% Fe) rock-salt structure to a biphasic NiO/NiFe₂O₄ (33 at.% Fe) heterostructure, a NiFe₂O₄ (66 at.% Fe) spinel structure, and eventually to α-Fe₂O₃ (100 at.% Fe). The efficient water-oxidation activity is ascribed to the highly mesoporous one-dimensional nanostructure, large surface area, and optimal amounts of the dopant Fe. The merits of abundance in the Earth, scalable synthesis, and highly efficient electrocatalytic activity make mesoporous Ni–Fe binary oxides promising oxygen-evolving catalysts for water splitting.