Chemoselective hydrodeoxygenation of vanillin is of great importance in converting biomass into high value-added chemicals. Herein, we describe a facile photochemical route to access palladium single atoms and clusters supported on silicoaluminophosphate-31 (SAPO-31) as a highly active, chemoselective, and reusable catalyst for hydrodeoxygenation of vanillin. Characterizations by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, extended X-ray absorption fine structure measurement, and CO-absorbed diffuse reflectance infrared Fourier transform spectroscopy reveal the atomically dispersed palladium single atoms and clusters are loosely bonded and randomly dispersed, without forming strong palladium-palladium metallic bonding, over the SAPO-31 support. This catalyst, with a full metal availability to the reactants, exhibits exceptional catalytic activity (TOF: 3,000 h⁻¹, Yield: > 99%) in the hydrodeoxygenation of vanillin toward 2-methoxy-4-methylphenol (MMP) under mild conditions (1 atm, 80 °C, 30 min), along with excellent stability, scalability (up to 100-fold), and wide substrate scope. The superior catalytic performance can be attributed to the synergistic effect of the positively charged palladium single atoms and fully exposed clusters, as well as the strong metal-support interactions. This work may offer a new avenue for the design and synthesis of fully exposed metal catalysts with targeted functionalities.

香草醛的化学选择性加氢脱氧对于将生物质转化为高附加值化学品具有重要意义。在此，我们描述了一种简便的光化学途径，用于获取负载在硅铝磷酸盐-31（SAPO-31）上的钯单原子和簇，作为香草醛加氢脱氧的高活性、化学选择性和可重复使用的催化剂。通过像差校正的高角度环形暗场扫描透射电子显微镜、扩展的 X 射线吸收精细结构测量和 CO 吸收漫反射红外傅里叶变换光谱的表征揭示了原子分散的钯单原子和簇是松散结合的和随机的分散在 SAPO-31 载体上，没有形成强的钯-钯金属键。这种催化剂，^-1 , 产率：> 99%) 在温和条件下（1 个大气压，80 °C，30 分钟）香草醛加氢脱氧生成 2-甲氧基-4-甲基苯酚 (MMP)，同时具有出色的稳定性、可扩展性（高达 100 -fold)，以及广泛的基材范围。优异的催化性能可归因于带正电荷的钯单原子和完全暴露的簇的协同作用，以及强大的金属-载体相互作用。这项工作可能为设计和合成具有目标功能的完全暴露的金属催化剂提供新的途径。