Abstract Herein, a new ternary-component layered double hydroxide (LDH) consisting of Ca2+ was constructed using an inexpensive bio-waste; eggshell, through a facile hydrothermal method (NiCaFe-LDH-H). The prepared material, NiCaFe-LDH-H, was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), N2 adsorption-desorption; Brunauer-Emmett-Teller (BET), difference thermogravimetry (DTG) and thermogravimetric analysis (TGA). Then, the NiCaFe-LDH-H was used as an electrocatalyst material to fabricate the modified carbon paste electrode (CPE) for water oxidation at neutral solutions (pH = 7.0). The electrochemical tests show that the NiCaFe-LDH-H modified CPE has efficient electrocatalytic activity towards the water oxidation reaction in a neutral solution. The effect of the LDH preparation method, presence of Ca2+ (as a low-cost material in comparison with transition metals), and its primary source was investigated on the electrocatalytic activity of the NiCaFe-LDH-H modified CPE and compared with binary-component LDHs (without Ca2+). The results of the electrochemical examinations indicate that the incorporation of Ca2+ from the eggshell source into the LDH by the hydrothermal method improve water oxidation performance of the NiCaFe-LDH-H modified CPE: lowering the onset potential to about 1.56 V vs. reversible hydrogen electrode (RHE) and overpotential to 373 mV in a neutral solution. The promoted electrocatalytic activity of the present modified CPE can be attributed to the high active surface area of the NiCaFe-LDH-H modified CPE due to the high crystallinity of LDH containing Ca2+.

中文翻译：

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新型三元层状双氢氧化物作为水氧化的低成本高效电催化剂：来自蛋壳生物废物的 NiCaFe-LDH

摘要 在此，利用廉价的生物废物构建了一种由 Ca2+ 组成的新型三元组分层状双氢氧化物 (LDH)；蛋壳，通过简单的水热法（NiCaFe-LDH-H）。制备的NiCaFe-LDH-H材料通过X射线衍射（XRD）、场发射扫描电子显微镜（FE-SEM）、N2吸附-解吸等表征；Brunauer-Emmett-Teller (BET)、差示热重分析 (DTG) 和热重分析 (TGA)。然后，NiCaFe-LDH-H 用作电催化剂材料来制造用于在中性溶液（pH = 7.0）下氧化水的改性碳糊电极（CPE）。电化学测试表明，NiCaFe-LDH-H 改性的 CPE 对中性溶液中的水氧化反应具有有效的电催化活性。LDH制备方法的效果，Ca2+（与过渡金属相比，作为一种低成本材料）的存在，其主要来源研究了 NiCaFe-LDH-H 改性 CPE 的电催化活性，并与二元组分 LDH（不含 Ca2+）进行了比较。电化学检测结果表明，通过水热法将蛋壳源中的 Ca2+ 引入 LDH 提高了 NiCaFe-LDH-H 改性 CPE 的水氧化性能：与可逆氢电极相比，起始电位降低至约 1.56 V (RHE) 和在中性溶液中的过电位为 373 mV。本改性 CPE 提高的电催化活性可归因于 NiCaFe-LDH-H 改性 CPE 的高活性表面积，这是由于含有 Ca2+ 的 LDH 的高结晶度。