The annual generation of coffee waste has overtaken 6 million metric tons, becoming a serious environmental problem. Herein, we report the fabrication of bimetallic electrocatalysts synthesized by 1) pyrolyzing spent coffee grounds (SCGs) at 400, 600, 800 and 1000 °C, 2) activating the as-obtained char with KOH and 3) functionalizing the activated carbon with iron(II) and manganese(II) phthalocyanine. The final electrocatalysts showed a high degree of amorphousness, defectivity (increasing with temperature) and high specific surface area (up to 1820 m g). In half-cell compartment (0.1 M KOH electrolyte), the top-notch material in terms of oxygen reduction reaction (ORR) activity and selectivity was CFeMn_600, which showed the same half-wave potential (E) compared to Pt/C standard along with a lower peroxide production. These outstanding results could be attributed to a high surface area, a Fe-Mn synergy, and an abundance of C-N defects. The performance of CFeMn_600 as a cathode material in alkaline exchange membrane fuel cells (AEMFC) showed an open circuit voltage (OCV) of 0.890 V and power density of 30 mW cm. Notwithstanding, this research is one of few cases where a waste-derived electrocatalyst is tested in a real AEMFC, thus becoming a pioneer in the fuel cell study of waste-derived electrode materials.

中文翻译：

---

来自废咖啡渣的氧还原反应无铂族金属电催化剂


每年产生的咖啡废物已超过600万吨，成为一个严重的环境问题。在此，我们报道了双金属电催化剂的合成方法：1）在 400、600、800 和 1000 °C 下热解废咖啡渣（SCG），2）用 KOH 活化所得炭，3）用铁功能化活性炭(II)和锰(II)酞菁。最终的电催化剂表现出高度的无定形性、缺陷度（随温度增加）和高比表面积（高达 1820 m g）。在半电池室（0.1 M KOH电解质）中，在氧还原反应（ORR）活性和选择性方面最好的材料是CFeMn_600，与Pt/C标准相比，它表现出相同的半波电位（E）具有较低的过氧化物产量。这些出色的结果可归因于高表面积、Fe-Mn 协同作用和丰富的 C-N 缺陷。 CFeMn_600作为碱性交换膜燃料电池（AEMFC）阴极材料的性能表现出0.890 V的开路电压（OCV）和30 mW cm的功率密度。尽管如此，这项研究是在真正的 AEMFC 中测试废物衍生电催化剂的少数案例之一，从而成为废物衍生电极材料燃料电池研究的先驱。