Mezza Alessio, Bartoli Mattia, Chiodoni Angelica, Zeng Juqin, Pirri Candido F, Sacco Adriano
Center for Sustainable Future Technologies @Polito, Istituto Italiano di Tecnologia, Via Livorno 60, 10144 Torino, Italy.
Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
Nanomaterials (Basel). 2023 Aug 12;13(16):2314. doi: 10.3390/nano13162314.
Gas-fed reactors for CO reduction processes are a solid technology to mitigate CO accumulation in the atmosphere. However, since it is necessary to feed them with a pure CO stream, a highly energy-demanding process is required to separate CO from the flue gasses. Recently introduced bicarbonate zero-gap flow reactors are a valid solution to integrate carbon capture and valorization, with them being able to convert the CO capture medium (i.e., the bicarbonate solution) into added-value chemicals, such as CO, thus avoiding this expensive separation process. We report here a study on the influence of the electrode structure on the performance of a bicarbonate reactor in terms of Faradaic efficiency, activity, and CO utilization. In particular, the effect of catalyst mass loading and electrode permeability on bicarbonate electrolysis was investigated by exploiting three commercial carbon supports, and the results obtained were deepened via electrochemical impedance spectroscopy, which is introduced for the first time in the field of bicarbonate electrolyzers. As an outcome of the study, a novel low-loaded silver-based electrode fabricated via the sputtering deposition technique is proposed. The silver mass loading was optimized by increasing it from 116 μg/cm to 565 μg/cm, thereby obtaining an important enhancement in selectivity (from 55% to 77%) and activity, while a further rise to 1.13 mg/cm did not provide significant improvements. The tremendous effect of the electrode permeability on activity and proficiency in releasing CO from the bicarbonate solution was shown. Hence, an increase in electrode permeability doubled the activity and boosted the production of in situ CO by 40%. The optimized Ag-electrode provided Faradaic efficiencies for CO close to 80% at a cell voltage of 3 V and under ambient conditions, with silver loading of 565 μg/cm, the lowest value ever reported in the literature so far.
用于一氧化碳还原过程的气体进料反应器是一种切实可行的技术，可减少大气中一氧化碳的积累。然而，由于需要向这些反应器中输入纯一氧化碳流，因此需要一个高能耗的过程来从烟道气中分离一氧化碳。最近引入的碳酸氢盐零间隙流动反应器是整合碳捕获和增值的有效解决方案，它们能够将一氧化碳捕获介质（即碳酸氢盐溶液）转化为增值化学品，如一氧化碳，从而避免了这种昂贵的分离过程。我们在此报告一项关于电极结构对碳酸氢盐反应器性能影响的研究，该影响涉及法拉第效率、活性和一氧化碳利用率。具体而言，通过使用三种商业碳载体研究了催化剂质量负载和电极渗透率对碳酸氢盐电解的影响，并通过电化学阻抗谱深化了所得结果，电化学阻抗谱在碳酸氢盐电解槽领域首次被引入。作为该研究的成果，提出了一种通过溅射沉积技术制造的新型低负载银基电极。通过将银质量负载从116μg/cm²增加到565μg/cm²对其进行了优化，从而在选择性（从55%提高到77%）和活性方面取得了显著提高，而进一步提高到1.13mg/cm²并未带来显著改善。结果表明电极渗透率对从碳酸氢盐溶液中释放一氧化碳的活性和效率有巨大影响。因此，电极渗透率的提高使活性提高了一倍，并使原位一氧化碳的产量提高了40%。在3V的电池电压和环境条件下，优化后的银电极在银负载为565μg/cm²时，对一氧化碳的法拉第效率接近80%，这是迄今为止文献中报道的最低值。
