Greenly Reduced CoFe‐PBA/Nickel Foam: A Robust Dual Electrocatalyst for Solar‐Driven Alkaline Water Electrolysis with a Low Cell Voltage

Greenly Synthesized CoPBA@PANI as a Proficient Electrocatalyst for Oxygen Evolution Reaction and Its Green Sustainability Assessments

Water electrolysis is a key factor to generate mobile and sustainable energy sources for H2 production. Cobalt-based Prussian Blue analogues encompassed with polymer support electrocatalysts CoPBAX@PANI (CoPBA@PANI-100, CoPBA@PANI-200, and CoPBA@PANI-300) have been synthesized and characterized. The well-designed CoPBA@PANI-200/GC shows a low overpotential (η10) of 301 mV with a small Tafel slope (56 mV dec-1), comapred to that of IrO2 (348 mV ; 98 mV dec-1) for OER. The conductivity with stability of CoPBAX@PANI have been increased due to the synergistic effect of CoPBA with PANI. PANI provides additional active sites and shows strong binding with Co ions, and the even distribution of CoPBA overcomes the sluggish kinetics. The turnover frequency (TOF) of CoPBA@PANI-200/GC (0.0212, s-1) was ∼15 times higher than IrO2 (0.0014 s-1) at 1.60 V. Furthermore, CoPBA@PANI-200/NF delivers low overpotential of 274 mV@10 mA cm-2 and exhibits a durability of >250 h with a potential loss of 4.2%. Benefiting from strong electronic interaction between polymer support and evenly distributed CoPBA, CoPBAx@PANI shows higher electrochemical active surface area (ECSA) of 53.08 mF cm-2. The solar-based water electrolysis confirmed the practical use of CoPBA@PANI-200/NF (1.57 V) for eco-benign industrial H2 production. The CoPBA@PANI-200 shows exceptional OER performances as well as favorable kinetics to resolve the sluggish water oxidation. Hence, the cost-effective CoPBA@PANI performances opens a prospective way to boost the efficiency of other cobalt-derived catalysts in renewable energy devices.

Synthesis of a carbon-wrapped microsphere MoO2/Mo2C heterojunction as an efficient electrocatalyst for the oxygen reduction reaction and the hydrogen evolution reaction

The development of non-noble metal catalysts for the optimization of conversion and storage devices is an important research topic. Hence, the microsphere MoO2/Mo2C/C heterojunction composites, which play an important role in the oxygen reduction reaction (ORR) and the hydrogen evolution reaction (HER), were synthesized using the solvothermal-sintering method. The results revealed that the as-prepared composite exhibited better ORR and HER catalytic performances than those of MoO2/Mo2C and Vulcan XC-72R (carbon black), and approaching that of commercial Pt/C. At the same time, it has a superior methanol tolerance and electrochemical stability than that of the commercial Pt/C. The excellent performance may be attributed to the synergistic effect of the MoO2/Mo2C heterostructure, highly conductive Vulcan XC-72R, and oxygen vacancies (Ov). This research offers new insights into the design and synthesis of cost-effective, environmentally friendly heterojunction composite catalysts used as a high-performance cathode material in fuel cells and water splitting.

Research on engineered electrocatalysts for efficient water splitting: a comprehensive review

Water electrolysis plays an interesting role toward hydrogen generation for overcoming global environmental crisis and solving the energy storage problem. However, there is still a deficiency of efficient electrocatalysts to overcome sluggish kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Great efforts have been employed to produce potential catalysts with low overpotential, rapid kinetics, and excellent stability for HER and OER. At present, hydrogen economy is driven by electrocatalysts with excellent characteristics; thus, systematic design strategy has become the driving force to exploit earth-abundant transition metal-based electrocatalysts toward H₂ economy. In this review, the recent progress on newer materials including metals, alloys, and transition metal oxides (manganese oxides, cobalt oxides, nickel oxides, PBA-derived metal oxides, and metal complexes) as photocatalysts/electrocatalysts has been overviewed together with some methodologies for efficient water splitting. Metal-organic framework (MOF)-based electrocatalysts have been highly exploited owing to their interesting functionalities. The photovoltaic-electrocatalytic (PV-EC) process focused on harvesting high solar-to-hydrogen efficiency (STH) among various solar energy conversion as well as storage systems. Electrocatalysts/photocatalysts with high efficiency have become an urgent need for overall water splitting. Also, cutting-edge achievements in the fabrication of electrocatalysts along with theoretical consideration have been discussed.