石墨炔（graphdiyne，GDY）是一种由sp及sp²杂化的碳原子共同构成的新型碳同素异形体，因其具有丰富的化学键、可调的电子结构、本征带隙、亚纳米层间距、丰富的表面化学及π共轭结构，在传感、催化、能源储存与生物医学等领域中备受关注。本论文利用石墨炔独特的性质，开展其在电催化和传感分析中的应用研究，取得的主要结果概述如下：

（1）石墨炔基钯微电极用于高选择性氧气活体传感研究：在本研究中，我们将GDY电沉积于碳纤维电极（carbon fiber electrode，CFE）上，利用无电沉积策略，制备了一种GDY基Pd微电极（Pd-CFE₁），该电极可在中性条件下有效实现四电子氧气（O₂）还原的电化学催化。实验结果表明，与利用电沉积法制备的Pd-CFE₂相比，Pd-CFE₁对过氧化氢（H₂O₂）的耐受性显著增强。进一步研究发现，利用疏水庚胺链吸附GDY，再利用无电沉积策略制备得到Pd-CFE₃，其对H₂O₂的耐受性可得到进一步提升。实验结果表明，Pd-CFE₃能够较好实现O₂的四电子还原，且可以避免H₂O₂还原的干扰。这可能是由于庚胺与GDY的修饰增加了电极的疏水性，使其不易吸附溶液中的H₂O₂，更易吸附空气中的O₂。在此基础上，我们利用Pd-CFE₃记录了大鼠吸入氮气（N₂）、O₂时脑内O₂含量的变化，发现大鼠在吸入O₂时，脑内的O₂浓度会迅速增加；在吸入N₂时，脑内的O₂浓度会迅速减少。在吸入空气一段时间后，鼠脑内的O₂浓度都恢复至初始状态。实验结果表明，Pd-CFE₃实现了鼠脑内O₂的高选择性、高稳定性活体传感。本研究为脑化学活体传感的研究提供了新的思路。

（2）氧化石墨炔基金属催化剂的制备及其电催化硝酸根还原产氨性能的研究：基于氧化石墨炔（graphdiyne oxide，GDYO）丰富的表面化学和可调的氧化还原能力，本研究利用无电沉积策略制备了GDYO基Ru催化剂（Ru-GDYO），探索了其电催化硝酸根还原产氨的性能。实验结果表明，Ru-GDYO可催化硝酸根还原产氨，反应的起始电位为-0.1 V（vs. RHE），产氨法拉第效率最高为57.4%，产率最高为1773 μg h^-1 cm^-2；进一步引入金属Co可以提升GDYO基金属催化剂（Ru+Co-GDYO）催化硝酸根还原的性能，反应的起始电位正移至+0.1 V（vs. RHE），产氨法拉第效率提高至77.5%，产率提高至6020 μg h^-1 cm^-2。机理研究发现，Ru+Co-GDYO电催化硝酸根还原产氨的过程可能涉及串联催化机制：Ru作为活性位点首先将一部分硝酸根还原为亚硝酸根，Co的引入可进一步催化亚硝酸根还原产氨，从而提升了GDYO基金属催化剂催化硝酸根还原产氨的性能。

（3）氧化石墨炔的自交联及其湿度传感性能研究：基于GDYO表面丰富的含氧官能团，探究了GDYO的脱水自交联反应及其在湿度传感中的应用。研究发现，在真空干燥的条件下，GDYO层间的羧基与羟基可以通过脱水酯化反应发生自交联。相较于在空气中干燥的GDYO，真空干燥条件下的GDYO对湿度的响应能力显著增强，且GDYO对湿度的响应能力受到真空干燥时间的影响，当真空干燥时间为8 h时，GDYO的湿度响应能力最好。

Graphdiyne (GDY) is a new carbon allotrope composed of sp and sp² hybrid carbon atoms. It has rich chemical bonds, adjustable electronic structure, intrinsic band gap, subnanometer layer spacing, rich surface chemistry and π-conjugated structure, showing promising applications in various research fields such as sensing, catalysis, energy conversion and storage and biomedicine. Aiming at in vivo sensing and electrocatalysis, this thesis focuses on the development of new GDY-based catalysts and sensors based on the unique properties of GDY. The main achievements are briefly summarized as follows:

(1) GDY-based palladium microelectrode for highly selective oxygen sensing in vivo. In this study, GDY was electrodeposited on carbon fiber electrode (CFE), and a GDY-based Pd microelectrode (Pd-CFE₁) was prepared via electroless deposition strategy, which can effectively achieve electrochemical catalysis of four-electron oxygen reduction under neutral conditions. Compared with Pd-CFE₂, which was prepared via electrodeposition strategy, Pd-CFE₁ displays enhanced H₂O₂ tolerance. Furthermore, when GDY is adsorbed by hydrophobic hexylamine on CFE and used as supporting substrate to anchor Pd nanoparticles via electroless deposition strategy (Pd-CFE₃), H₂O₂ tolerance is further improved. The experimental results show that Pd-CFE₃ can achieve four-electron reduction of O₂ and avoid the interference of H₂O₂ reduction. This may be because the modification of heptylamine and GDY increases the hydrophobicity of the electrode, thus making it prefer to adsorb O₂ in air rather than H₂O₂ in solution. We thus used Pd-CFE₃ for in vivo sensing of O₂ in rat brain and the results show that relative to the O₂ level obtained with the animal under normal conditions (i.e., spontaneously breathing air), breathing pure O₂ gas (i.e., hyperoxia) rapidly increased the O₂ level in rat brain, while breathing pure N₂ (i.e., hypoxia) decreased the O₂ level in rat brain. The current responses under both hyperoxia and hypoxia conditions returned to the basal level with spontaneous air breathing. Both in vitro and in vivo experiments demonstrate that Pd-CFE₃ shows a high selectivity and stability useful for reliable measurements of O₂ in rat brain. This study broadens the application of GDY in the electrochemical sensing in vivo.

(2) Design of graphdiyne oxide (GDYO)-based metal electrocatalysts for nitrate reduction to ammonia (NO₃RR). GDYO that possesses diverse surface chemical properties and tunable redox capability is proved as a promising supporting substrate material. In this study, we prepared GDYO-based Ru nanoparticles (Ru-GDYO) via electroless deposition method, and investigated its electrocatalytic activity in NO₃RR. The experimental results show that Ru-GDYO can catalyze NO₃RR with an onset potential of -0.1 V (vs. RHE), a maximum NH₃-Faradaic efficiency of 57.4% and a maximum NH₃ yield of 1773 μg h^-1 cm^-2. We next introduced metal Co into Ru-GDYO to prepare the Ru+Co-GDYO electrocatalyst, and found that the introduction of Co could improve the catalytic performance of NO₃RR with an onset potential of +0.1 V (vs. RHE), a maximum NH₃-Faradaic efficiency of 77.5% and a maximum NH₃ yield of 6020 μg h^-1 cm^-2. Mechanistic studies reveal that the NO₃RR activity of Ru+Co-GDYO may arise from the tandem catalysis mechanism, that is, Ru sites activate nitrate to form nitrite, and Co sites further reduce nitrite to produce ammonia, thus enhancing the electrocatalytic performance of NO₃RR.

(3) The self-crosslinking reaction of GDYO and study on its humidity sensing performance. Based on the abundant oxygen-containing functional groups on the surface of GDYO, we explored the dehydration self-crosslinking reaction of GDYO and investigated its performance in humidity sensing. It was found that dehydration by vacuum drying triggers self-crosslinking of GDYO sheets and drastically enhances their humidity sensing performance. Spectroscopical studies support the formation of new ester bonds, suggesting a condensation-esterification reaction between GDYO sheets. Compared with GDYO dried in air, GDYO dried under vacuum shows significantly enhanced humidity sensing performance, which is affected by the vacuum drying time. The experimental results show that the humidity response ability of GDYO is the best when the vacuum drying time is 8 hours.