The development of effective and inexpensive hydrogen evolution reaction (HER) electrocatalysts for future renewable energy systems is highly desired. The strongly acidic conditions in proton exchange membranes create a need for acid-stable HER catalysts. A nanohybrid that consists of carbon nanotubes decorated with CoP nanocrystals (CoP/ CNT) was prepared by the low-temperature phosphidation of a Co 3 O 4 /CNT precursor. As a novel non-noble-metal HER catalyst operating in acidic electrolytes, the nanohybrid exhibits an onset overpotential of as low as 40 mV, a Tafel slope of 54 mV dec À1 , an exchange current density of 0.13 mA cm À2 , and a Faradaic efficiency of nearly 100 %. This catalyst maintains its catalytic activity for at least 18 hours and only requires overpotentials of 70 and 122 mV to attain current densities of 2 and 10 mA cm À2 , respectively.

Iron is the cheapest and one of the most abundant transition metals. Natural [FeFe]-hydrogenases exhibit remarkably high activity in hydrogen evolution, but they suffer from high oxygen sensitivity and difficulty in scale-up. Herein, an FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its b-FeOOH NA/Ti precursor through a lowtemperature phosphidation reaction. When applied as selfsupported 3D hydrogen evolution cathode, the FeP NA/Ti electrode shows exceptionally high catalytic activity and good durability, and it only requires overpotentials of 55 and 127 mV to afford current densities of 10 and 100 mA cm 2 , respectively. The excellent electrocatalytic performance is promising for applications as non-noble-metal HER catalyst with a high performance-price ratio in electrochemical water splitting for large-scale hydrogen fuel production.

Electrocatalytic two‐electron oxygen reduction has emerged as a promising alternative to the energy‐ and waste‐intensive anthraquinone process for distributed H2O2 production. This process, however, suffers from strong competition from the four‐electron pathway leading to low H2O2 selectivity. Herein, we report using a superhydrophilic O2‐entrapping electrocatalyst to enable superb two‐electron oxygen reduction electrocatalysis. The honeycomb carbon nanofibers (HCNFs) are robust and capable of achieving a high H2O2 selectivity of 97.3 %, much higher than that of its solid carbon nanofiber counterpart. Impressively, this catalyst achieves an ultrahigh mass activity of up to 220 A g−1, surpassing all other catalysts for two‐electron oxygen reduction reaction. The superhydrophilic porous carbon skeleton with rich oxygenated functional groups facilitates efficient electron transfer and better wetting of the catalyst by the electrolyte, and the interconnected cavities allow for more effective entrapping of the gas bubbles. The catalytic mechanism is further revealed by in situ Raman analysis and density functional theory calculations.

Electrochemical CO2 reduction under ambient conditions is a promising pathway for conversion of CO2 into value‐added products. In recent years, great achievements have been obtained in the understanding the mechanism and development of efficient and selective catalysts for electrochemical CO2 reduction. However, the electrochemical CO2 reduction is still far from practical applications. Based on the gap between current research and practical applications, the state‐of‐the‐art of the theoretical and experiment investigations on different electrocatalysts for the electrocatalysis of CO2 to CH4 is systematically and constructively reviewed. First of all, strategies for enhancing the catalytic activity and selectivity of electrochemical reduction of CO2 to CH4 are also examined in this review. The modulated strategies mainly involve the following aspects: i) tuning the applied potentials, ii) morphology engineering, iii) crystallographic facets engineering, iv) defect engineering, v) alloying. Furthermore, the influence of the electrolyte on the activity and selectivity for electrocatalysis of CO2 to CH4 is also reviewed. This review will build a systematic understanding in the electrochemical CO2 reduction to CH4 and may help to provide new insight for designing and optimizing the catalysts and/or electrolyte.

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