Enhanced mass transfer with amphiphilic CoOx/biochar for photocatalytic CO2 conversion

• Amphiphilic CoO x /biochar was constructed for photocatalytic CO 2 conversion. • Micro-/nanostructures derived from loofa sponge and CoO x endowed CDB-3 with amphiphilic properties. • Amphiphilic surface improved the CO 2 mass transfer over the catalyst. • CDB-3 exhibited an efficient photocatalytic CO 2 conversion with a turnover frequency (TOF) of 0.29 s -1 and CO production of 48.3 umol/h. Special wetting ability of catalyst plays an important role in photocatalytic CO 2 conversion. Herein, we find that amphiphilic CoO x /biochar (CDB) with a synergistic effect is beneficial for the photocatalytic CO 2 conversion. Contact angle experiments display that the amphiphilic performance of CDB-3 (amphiphilic CoO x /biochar with 3.0% wt. cobalt) is due to the formed micro-/nanostructures stemmed from loofa sponge and CoO x . The contact angle of molecular CO 2 on CDB-3 is 69.6° in the reaction system. CO 2 -temperature programmed desorption and polarization curves demonstrate that amphiphilic surface increases the CO 2 mass transfer. Photoluminescence (PL) spectra shows that CDB-3 has an optimized carrier migration efficiency. Therefore, CDB-3 exhibits an efficient photocatalytic CO 2 conversion with a turnover frequency (TOF) of 0.29 s -1 and CO production rate of 48.3 umol/h, which is a 3.4-fold than pure CDB.